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/eventfilter.h

@@ -59,7 +59,7 @@ public:
 
 private:
     // Objects of this class are made to be stored in a linked list in
-    // wxEvtHandler so put the next node ponter directly in the class itself.
+    // wxEvtHandler so put the next node pointer directly in the class itself.
     wxEventFilter* m_next;
 
     // And provide access to it for wxEvtHandler [only].