Blender Git Loki

Here lies a final attempt attempt at a sane Wintab implementation, smashed
against the reality of broken and bad APIs. If only rawinput events
mapped consistently, but for reasons unknown Wintab express buttons will
map to the device when stylus is in range, and map to an emulated button
when the pen is away. For this reason this commit must only exist for
posterity, a totem of my naivety in believing Wintab and Win32 could
be reasoned with.