libtorc-baseui: Remove glext.h

- no longer needed for the windows build
libs: Add directx headers from mingw-64 project

These can probably be removed at a later date as mingw-64 will probably
become the default.
libtorc-audio: Use the mingw-64 dsound header
libtorc-baseui: Add UIDirect3D9Window and associated classes.

This is feature equivalent to the OpenGL classes (with the same
performance tweaks needed) and is the default for windows builds.