Make all wxMask constructors use the C++ (bitmap, colour) ctor, and

Make all wxMask constructors use the C++ (bitmap, colour) ctor, and
then just default in BLACK to simulate the default (monobitmap)
behaviour.  It's too tricky to make true monochome bitmaps in a
platform independent way from the Python wrappers.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@25787 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775