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/icon.tex

@@ -212,10 +212,8 @@ must have mask colour set.
 
 \func{}{\destruct{wxIcon}}{\void}
 
-Destroys the wxIcon object and possibly the underlying icon data.
-Because reference counting is used, the icon may not actually be
-destroyed at this point - only when the reference count is zero will the
-data be deleted.
+Destructor.
+See \helpref{reference-counted object destruction}{refcountdestruct} for more info.
 
 If the application omits to delete the icon explicitly, the icon will be
 destroyed automatically by wxWidgets when the application exits.
@@ -355,9 +353,7 @@ Sets the width member (does not affect the icon data).
 
 \func{wxIcon\& }{operator $=$}{\param{const wxIcon\& }{icon}}
 
-Assignment operator. This operator does not copy any data, but instead
-passes a pointer to the data in {\it icon} and increments a reference
-counter. It is a fast operation.
+Assignment operator, using \helpref{reference counting}{trefcount}.
 
 \wxheading{Parameters}
 
@@ -367,34 +363,4 @@ counter. It is a fast operation.
 
 Returns 'this' object.
 
-\membersection{wxIcon::operator $==$}\label{wxiconequal}
-
-\func{bool}{operator $==$}{\param{const wxIcon\& }{icon}}
-
-Equality operator. This operator tests whether the internal data pointers are
-equal (a fast test).
-
-\wxheading{Parameters}
-
-\docparam{icon}{Icon to compare with 'this'}
-
-\wxheading{Return value}
-
-Returns true if the icons were effectively equal, false otherwise.
-
-\membersection{wxIcon::operator $!=$}\label{wxiconnotequal}
-
-\func{bool}{operator $!=$}{\param{const wxIcon\& }{icon}}
-
-Inequality operator. This operator tests whether the internal data pointers are
-unequal (a fast test).
-
-\wxheading{Parameters}
-
-\docparam{icon}{Icon to compare with 'this'}
-
-\wxheading{Return value}
-
-Returns true if the icons were unequal, false otherwise.
-