Add support for editing dates (without time) to wxGrid

Add wxGridCellDateRenderer and wxGridCellDateRenderer which can be used
for the grid cells containing only dates, without times.

Also add wxGrid::SetColFormatDate() convenience function.

Refactor wxGridCellDateTimeRenderer slightly to reuse its code.

Closes https://github.com/wxWidgets/wxWidgets/pull/1101

interface/wx/grid.h

@@ -142,6 +142,50 @@ public:
     wxGridCellBoolRenderer();
 };
 
+/**
+    @class wxGridCellDateRenderer
+
+    This class may be used to show a date, without time, in a cell.
+
+    See @ref wxGridCellDateTimeRenderer for a date/time version.
+    wxDateTime::Format() is used internally to render the date
+    representation. wxDateTime::ParseDate() is used to parse the string
+    data entered in the cell.
+
+    @library{wxcore}
+    @category{grid}
+
+    @see wxGridCellRenderer, wxGridCellAutoWrapStringRenderer,
+         wxGridCellBoolRenderer, wxGridCellEnumRenderer,
+         wxGridCellFloatRenderer, wxGridCellNumberRenderer,
+         wxGridCellStringRenderer, wxGridCellDateTimeRenderer
+
+    @since 3.1.3
+*/
+class wxGridCellDateRenderer : public wxGridCellStringRenderer
+{
+public:
+    /**
+        Date renderer constructor.
+
+        @param outformat
+            strftime()-like format string used to render the output date.
+            By default (or if provided format string is empty) localized
+            date representation ("%x") is used.
+    */
+    wxGridCellDateRenderer(const wxString& outformat = wxString());
+
+
+    /**
+        Sets the strftime()-like format string which will be used to render
+        the date.
+
+        @param params
+            strftime()-like format string used to render the date.
+    */
+    virtual void SetParameters(const wxString& params);
+};
+
 /**
     @class wxGridCellDateTimeRenderer
 
@@ -155,9 +199,9 @@ public:
     @see wxGridCellRenderer, wxGridCellAutoWrapStringRenderer,
          wxGridCellBoolRenderer, wxGridCellEnumRenderer,
          wxGridCellFloatRenderer, wxGridCellNumberRenderer,
-         wxGridCellStringRenderer
+         wxGridCellStringRenderer, wxGridCellDateRenderer
 */
-class wxGridCellDateTimeRenderer : public wxGridCellStringRenderer
+class wxGridCellDateTimeRenderer : public wxGridCellDateRenderer
 {
 public:
     /**
@@ -384,7 +428,7 @@ public:
     @see wxGridCellAutoWrapStringEditor, wxGridCellBoolEditor,
          wxGridCellChoiceEditor, wxGridCellEnumEditor,
          wxGridCellFloatEditor, wxGridCellNumberEditor,
-         wxGridCellTextEditor
+         wxGridCellTextEditor, wxGridCellDateEditor
 */
 class wxGridCellEditor : public wxClientDataContainer, public wxRefCounter
 {
@@ -532,7 +576,8 @@ protected:
 
     @see wxGridCellEditor, wxGridCellBoolEditor, wxGridCellChoiceEditor,
          wxGridCellEnumEditor, wxGridCellFloatEditor,
-         wxGridCellNumberEditor, wxGridCellTextEditor
+         wxGridCellNumberEditor, wxGridCellTextEditor,
+         wxGridCellDateEditor
 */
 class wxGridCellAutoWrapStringEditor : public wxGridCellTextEditor
 {
@@ -551,7 +596,7 @@ public:
     @see wxGridCellEditor, wxGridCellAutoWrapStringEditor,
          wxGridCellChoiceEditor, wxGridCellEnumEditor,
          wxGridCellFloatEditor, wxGridCellNumberEditor,
-         wxGridCellTextEditor
+         wxGridCellTextEditor, wxGridCellDateEditor
 */
 class wxGridCellBoolEditor : public wxGridCellEditor
 {
@@ -590,7 +635,7 @@ public:
     @see wxGridCellEditor, wxGridCellAutoWrapStringEditor,
          wxGridCellBoolEditor, wxGridCellEnumEditor,
          wxGridCellFloatEditor, wxGridCellNumberEditor,
-         wxGridCellTextEditor
+         wxGridCellTextEditor, wxGridCellDateEditor
 */
 class wxGridCellChoiceEditor : public wxGridCellEditor
 {
@@ -641,7 +686,7 @@ public:
     @see wxGridCellEditor, wxGridCellAutoWrapStringEditor,
          wxGridCellBoolEditor, wxGridCellChoiceEditor,
          wxGridCellTextEditor, wxGridCellFloatEditor,
-         wxGridCellNumberEditor
+         wxGridCellNumberEditor, wxGridCellDateEditor
 */
 class wxGridCellEnumEditor : public wxGridCellChoiceEditor
 {
@@ -666,7 +711,7 @@ public:
     @see wxGridCellEditor, wxGridCellAutoWrapStringEditor,
          wxGridCellBoolEditor, wxGridCellChoiceEditor,
          wxGridCellEnumEditor, wxGridCellFloatEditor,
-         wxGridCellNumberEditor
+         wxGridCellNumberEditor, wxGridCellDateEditor
 */
 class wxGridCellTextEditor : public wxGridCellEditor
 {
@@ -705,7 +750,7 @@ public:
     @see wxGridCellEditor, wxGridCellAutoWrapStringEditor,
          wxGridCellBoolEditor, wxGridCellChoiceEditor,
          wxGridCellEnumEditor, wxGridCellNumberEditor,
-         wxGridCellTextEditor
+         wxGridCellTextEditor, wxGridCellDateEditor
 */
 class wxGridCellFloatEditor : public wxGridCellTextEditor
 {
@@ -743,7 +788,7 @@ public:
     @see wxGridCellEditor, wxGridCellAutoWrapStringEditor,
          wxGridCellBoolEditor, wxGridCellChoiceEditor,
          wxGridCellEnumEditor, wxGridCellFloatEditor,
-         wxGridCellTextEditor
+         wxGridCellTextEditor, wxGridCellDateEditor
 */
 class wxGridCellNumberEditor : public wxGridCellTextEditor
 {
@@ -775,6 +820,32 @@ protected:
     wxString GetString() const;
 };
 
+/**
+    @class wxGridCellDateEditor
+
+    Grid cell editor for dates.
+
+    Uses @ref wxDatePickerCtrl as actual edit control.
+
+    @library{wxcore}
+    @category{grid}
+
+    @see wxGridCellEditor, wxGridCellAutoWrapStringEditor,
+         wxGridCellBoolEditor, wxGridCellChoiceEditor,
+         wxGridCellEnumEditor, wxGridCellFloatEditor,
+         wxGridCellTextEditor
+
+    @since 3.1.3
+*/
+class wxGridCellDateEditor : public wxGridCellEditor
+{
+public:
+    /**
+        Date editor constructor.
+    */
+    wxGridCellDateEditor();
+};
+
 
 
 /**
@@ -2080,6 +2151,8 @@ enum wxGridRenderStyle
     - wxGridCellFloatRenderer
     - wxGridCellNumberRenderer
     - wxGridCellStringRenderer
+    - wxGridCellDateRenderer
+    - wxGridCellDateTimeRenderer
 
     The look of a cell can be further defined using wxGridCellAttr. An object
     of this type may be returned by wxGridTableBase::GetAttr().
@@ -2092,6 +2165,7 @@ enum wxGridRenderStyle
     - wxGridCellFloatEditor
     - wxGridCellNumberEditor
     - wxGridCellTextEditor
+    - wxGridCellDateEditor
 
     Please see wxGridEvent, wxGridSizeEvent, wxGridRangeSelectEvent, and
     wxGridEditorCreatedEvent for the documentation of all event types you can
@@ -2961,9 +3035,10 @@ public:
             Name of the new type. May be any string, but if the type name is
             the same as the name of an already registered type, including one
             of the standard ones (which are @c wxGRID_VALUE_STRING, @c
-            wxGRID_VALUE_BOOL, @c wxGRID_VALUE_NUMBER, @c wxGRID_VALUE_FLOAT
-            and @c wxGRID_VALUE_CHOICE), then the new registration information
-            replaces the previously used renderer and editor.
+            wxGRID_VALUE_BOOL, @c wxGRID_VALUE_NUMBER, @c wxGRID_VALUE_FLOAT,
+            @c wxGRID_VALUE_CHOICE and @c wxGRID_VALUE_DATE), then the new
+            registration information replaces the previously used renderer and
+            editor.
         @param renderer
             The renderer to use for the cells of this type. Its ownership is
             taken by the grid, i.e. it will call DecRef() on this pointer when
@@ -3090,6 +3165,19 @@ public:
     */
     void SetColFormatNumber(int col);
 
+    /**
+        Sets the specified column to display date values.
+
+        The @a format argument is used with wxGridCellDateRenderer and allows
+        to specify the strftime-like format string to use for displaying the
+        dates in this column.
+
+        @see SetColFormatCustom()
+
+        @since 3.1.3
+    */
+    void SetColFormatDate(int col, const wxString& format = wxString());
+
     /**
         Sets the default editor for grid cells.