Added class groups example to Doxygen and added parent "Functions and Macros", and "Classes by Category" groups.

Also added CSS to add "Categories / " to the "Modules" tab label, and turned on DETAILS_AT_TOP setting.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@52454 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/bitmap.h

@@ -147,6 +147,7 @@ public:
 
 /**
     @class wxBitmap
+    @ingroup group_class_gdi
     @wxheader{bitmap.h}
 
     This class encapsulates the concept of a platform-dependent bitmap,
@@ -724,6 +725,7 @@ wxBitmap wxNullBitmap;
 
 /**
     @class wxMask
+    @ingroup group_class_gdi
     @wxheader{bitmap.h}
 
     This class encapsulates a monochrome mask bitmap, where the masked area is