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/motif/choice.h

@@ -102,7 +102,7 @@ public:
 protected:
     // minimum size for the text ctrl
     wxSize GetItemsSize() const;
-    // common part of all contructors
+    // common part of all constructors
     void Init();
 
     WXWidget      m_menuWidget;