This fully threads both the real minimum size of the texture and the
dimensions of the texture through to the TA parameters.
This also removes spurious zero-area drawing commands (space
characters).
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.
I think the original version is more readable, but the newer version
is better overall because it doesn't require reading from dst, and is
able to directly write to a 32-bit dst.
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).
