VxD hooks for WinOS2.
This seems to solve all the remaining problems with Win3.1, namely:
- Alt-Tab now works (SHELL VxD)
- Timer now works (VTDAPI VxD)

Note: win32s support is disabled for now - it needs some porting efforts and
I have lost my test-cases for it.
Note: Only protected mode entry points are supported. WinOS2 doesnt seem to
be using the real-mode entry points, so I have not added those.

It seems Win3.1/WinOS2 works perfectly now as far as I can tell, at least
similar to how it works under QDPMI.


git-svn-id: https://dosemu.svn.sourceforge.net/svnroot/dosemu/trunk@533 7758b857-130e-0410-ab9c-d8735a528d18