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/pen.tex

@@ -154,12 +154,10 @@ is found in the colour database.
 \func{}{\destruct{wxPen}}{\void}
 
 Destructor.
+See \helpref{reference-counted object destruction}{refcountdestruct} for more info.
 
 \wxheading{Remarks}
 
-The destructor may not delete the underlying pen object of the native windowing
-system, since wxBrush uses a reference counting system for efficiency.
-
 Although all remaining pens are deleted when the application exits,
 the application should try to clean up all pens itself. This is because
 wxWidgets cannot know if a pointer to the pen object is stored in an
@@ -335,17 +333,15 @@ Assignment operator, using \helpref{reference counting}{trefcount}.
 
 \func{bool}{operator $==$}{\param{const wxPen\& }{pen}}
 
-Equality operator. Two pens are equal if they contain pointers
-to the same underlying pen data. It does not compare each attribute,
-so two independently-created pens using the same parameters will
-fail the test.
+Equality operator.
+See \helpref{reference-counted object comparison}{refcountequality} for more info.
 
 \membersection{wxPen::operator $!=$}\label{wxpennotequals}
 
 \func{bool}{operator $!=$}{\param{const wxPen\& }{pen}}
 
-Inequality operator. Two pens are not equal if they contain pointers
-to different underlying pen data. It does not compare each attribute.
+Inequality operator.
+See \helpref{reference-counted object comparison}{refcountequality} for more info.
 
 \section{\class{wxPenList}}\label{wxpenlist}