Extend the bitfields of these instructions: BitmapHandle, ClearTag, Tag, BitmapSource, PaletteSource
Add instructions: BitmapSourceH PaletteSourceH
All the new bits and opcodes are ignored by earlier hardware, so this change is backwards-compatible.
Passes tests on all EVE hardware.
The setmodel() method controls the behavior
So existing code will continue to work unchanged
Subsequent releases of the ``eve`` library will call setmodel() to enable the new behavior
Confirmed all code paths on EVE hardware
Changed calls: PointSize(), LineWidth(), VertexTranslateX() and VertexTranslateY()
Units for all the above are now pixels, not fixed-point integers. This matches OpenGL.
Docstrings updated accordingly
