#11 Support for wxEVT_COMMAND_AUINOTEBOOK_PAGE_CLOSED

[FGI]

This adds support for the wxEVT_COMMAND_AUINOTEBOOK_PAGE_CLOSED event, which is triggered right after a page of an AUI notebook was closed. There is already support for the wxEVT_COMMAND_AUINOTEBOOK_PAGE_CLOSE event, however this is triggered when the page is being about to close, i.e. right before the page is closed.
Works for me, but only tested with C++ code generator.

[ryanjmulder]

committed in revision 2230