Ensure rgb values are integers

git-svn-id: http://svn.wxwidgets.org/svn/wx/wxPython@74103 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Add wxIcon(const wxBitmap& bmp) constructor

git-svn-id: http://svn.wxwidgets.org/svn/wx/wxPython@74104 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775