First cut at a tool to create full color (16 bit) image resources.
Fixed mkimage.py so that QMG output is limited to 256x256 pixels.
Filled out implementation of 'DrawImage16()' for full color images.
Part of issue #3.
Fixed a bug calculating line length in bytes for images.
Cleaned up API for image drawing (see issue #4), removed the concept
of 'registered' assets and now have full support for 1bpp, 4bpp and
16bpp images (see issue #3).
Moved font rendering support to the graphics driver level and out of
the framework. This fixes #9.