Add wxSpinCtrl::SetBase() to allow entering hexadecimal numbers.

Add a generic SetBase() API even though right now only bases 10 and 16 are
supported as we might support other ones (e.g. 8?) in the future. Implement it
for MSW, GTK and generic versions.

Add controls allowing to test this feature to the widgets sample.

Add "base" property support to the XRC handler for wxSpinCtrl, document it and
test it in the xrc sample.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72414 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/spinctrl.h

@@ -62,6 +62,11 @@ public:
     // another wxTextCtrl-like method
     void SetSelection(long from, long to);
 
+    // wxSpinCtrlBase methods
+    virtual int GetBase() const;
+    virtual bool SetBase(int base);
+
+
     // implementation only from now on
     // -------------------------------
 
@@ -148,6 +153,12 @@ private:
     // Common part of all ctors.
     void Init();
 
+    // Adjust the text control style depending on whether we need to enter only
+    // digits or may need to enter something else (e.g. "-" sign, "x"
+    // hexadecimal prefix, ...) in it.
+    void UpdateBuddyStyle();
+
+
     DECLARE_DYNAMIC_CLASS(wxSpinCtrl)
     DECLARE_EVENT_TABLE()
     wxDECLARE_NO_COPY_CLASS(wxSpinCtrl);