COW cleanup patch (1583966):

1. perform deep comparison for the classes for which it makes sense in the
   ports where this wasn't done yet
2. remove (shallow) comparison operators for the classes for which it does
   not make sense (such as wxBitmap)
3. makes wxBitmap use COW on all ports
4. adds wxObject::IsRefTo()
5. centralizes and improves COW docs


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@42752 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/latex/wx/cursor.tex

@@ -229,7 +229,10 @@ wxCursor down_cursor = wxCursor(down_bits, 32, 32,
 
 \func{}{\destruct{wxCursor}}{\void}
 
-Destroys the cursor. A cursor can be reused for more
+Destroys the cursor.
+See \helpref{reference-counted object destruction}{refcountdestruct} for more info.
+
+A cursor can be reused for more
 than one window, and does not get destroyed when the window is
 destroyed. wxWidgets destroys all cursors on application exit, although
 it is best to clean them up explicitly.
@@ -246,20 +249,3 @@ Returns true if cursor data is present.
 
 Assignment operator, using \helpref{reference counting}{trefcount}.
 
-\membersection{wxCursor::operator $==$}\label{wxcursorequals}
-
-\func{bool}{operator $==$}{\param{const wxCursor\& }{cursor}}
-
-Equality operator. Two cursors are equal if they contain pointers
-to the same underlying cursor data. It does not compare each attribute,
-so two independently-created cursors using the same parameters will
-fail the test.
-
-\membersection{wxCursor::operator $!=$}\label{wxcursornotequals}
-
-\func{bool}{operator $!=$}{\param{const wxCursor\& }{cursor}}
-
-Inequality operator. Two cursors are not equal if they contain pointers
-to different underlying cursor data. It does not compare each attribute.
-
-