First of a series of TrueType hinting patches.

This one models the TT "graphics state" which is essentially all of the data involving outlines, measurement and rounding.

Includes a tiny math module that provides support for working with fixed point values as raw i32s. This is not ideal but exists from the initial port from FreeType and will require some time and attention to correct. This will need to be deferred to a later time.

- add links to table containing default values for graphics state
- add tests for new fixed point math functions