Allow hiding/showing already hidden/shown wxGrid rows/columns.

Don't assert if an already hidden/shown row/column is being hidden/shown again
but simply don't do anything. This is more convenient because the code outside
wxGrid has no efficient way to only hide a row/column if it's currently shown.

Closes #14960.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73366 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/grid.h

@@ -2988,8 +2988,7 @@ public:
         To show the column later you need to call SetColSize() with non-0
         width or ShowCol() to restore the previous column width.
 
-        Notice that this method shouldn't be called if the column is already
-        hidden.
+        If the column is already hidden, this method doesn't do anything.
 
         @param col
             The column index.
@@ -3002,8 +3001,7 @@ public:
         The column is shown again with the same width that it had before
         HideCol() call.
 
-        Notice that this method shouldn't be called if the column is not
-        currently hidden.
+        If the column is currently shown, this method doesn't do anything.
 
         @see HideCol(), SetColSize()
      */
@@ -3073,6 +3071,8 @@ public:
         To show the row later you need to call SetRowSize() with non-0
         width or ShowRow() to restore its original height.
 
+        If the row is already hidden, this method doesn't do anything.
+
         @param col
             The row index.
      */
@@ -3084,6 +3084,8 @@ public:
         The row is shown again with the same height that it had before
         HideRow() call.
 
+        If the row is currently shown, this method doesn't do anything.
+
         @see HideRow(), SetRowSize()
      */
     void ShowRow(int col);