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/wxcrt.h

@@ -490,7 +490,7 @@ inline int wxStrcoll_String(const wxString& s1, const T& s2)
 }
 
 #ifndef wxNEEDS_DECL_BEFORE_TEMPLATE
-// this is exactly the same WX_STRCMP_FUNC line as above, insde the
+// this is exactly the same WX_STRCMP_FUNC line as above, inside the
 // wxNEEDS_DECL_BEFORE_TEMPLATE case
 WX_STRCMP_FUNC(wxStrcoll, wxCRT_StrcollA, wxCRT_StrcollW, wxStrcoll_String)
 #endif