Fix spelling in comments and documentation using codespell

Apply the utility from https://github.com/codespell-project/codespell/
to fix spelling issues in the headers under both include and interface
directories and add a file with a couple of exceptions.

The exact command line used was:

    $ codespell -w -I misc/scripts/codespell.ignore -i 3 in*

include/wx/osx/app.h

@@ -77,7 +77,7 @@ public:
     { m_macCurrentEvent = event ; m_macCurrentEventHandlerCallRef = handler ; }
 
     // adding a CFType object to be released only at the end of the current event cycle (increases the
-    // refcount of the object passed), needed in case we are in the middle of an event concering an object
+    // refcount of the object passed), needed in case we are in the middle of an event concerning an object
     // we want to delete and cannot do it immediately
     // TODO change semantics to be in line with cocoa (make autrelease NOT increase the count)
     void                  MacAddToAutorelease( void* cfrefobj );