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/hash.h

@@ -119,7 +119,7 @@ private:
     void DoRemoveNode( wxHashTableBase_Node* node );
 
     // destroys data contained in the node if appropriate:
-    // deletes the key if it is a string and destrys
+    // deletes the key if it is a string and destroys
     // the value if m_deleteContents is true
     void DoDestroyNode( wxHashTableBase_Node* node );