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/clrpicker.h

@@ -74,7 +74,7 @@ protected:
 // under the name "wxColourPickerWidget".
 // NOTE: wxColourPickerCtrl allocates a wxColourPickerWidget and relies on the
 //       fact that all classes being mapped as wxColourPickerWidget have the
-//       same prototype for their contructor (and also explains why we use
+//       same prototype for their constructor (and also explains why we use
 //       define instead of a typedef)
 // since GTK > 2.4, there is GtkColorButton
 #if defined(__WXGTK20__) && !defined(__WXUNIVERSAL__)