File Loading Bugfix

Fixed a bug in ForeignKey.mapsToPrimary() which prevented linking tables
that didn't match the primary key of their targets from mapping
correctly.
Menu adjustments for progressbar

Improved the way that menus handle having the progress bar taking up the
top part of the screen.
HeightMap 1

Added rough implementation of the heightmap. Added a custom shader for a
red-yellow-green transition on the bars, and created a caching system
for multiattribute instance counts. Still some bugs to work out in the
cache.