Also adds the incomplete modifier_volume example.
This also adds vec2 for UV coordinates, and obj_to_cpp has been
modified to parse vertex texture coordinates from obj files.
This still needs to be cleaned up, particularly to properly pass the
texture size around--there are a few unnecessary '128x256' magic
numbers scattered in the code.
This is very barebones, and uses the serial interface to communicate
the status of the "a" controller button being pressed.
I'd like to make this a more interactive/graphical demo.
This also adds ta_parameter_writer; I am not certain if I like this,
but it felt necessary to deal with ta_parameters being either 32 or 64
bytes long--for this reason, a reinterpret_cast to a union is less
attractive (the union members are not a fixed size).
