A couple of changes to wxImage:

1. changed wxBMP_foo, wxCUR_foo to wxIMAGE_OPTION_{BMP,CUR}_foo
   (with backward compatiblity macros, of course)
2. applied Chris' patch to update hotspot when scaling an image
3. applied Chris' patch to write a filename in XPM and generalized it
   to pass wxIMAGE_OPTION_FILENAME to all saving handlers

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@14247 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775