Forgot to initialize a variable in targa.c's load_header and now
I look SUCH. AN. IDIOT.
Forgot to check a pointer returned by malloc in load_targa
ported over a PCX loader from another pet project I made a few years ago in C++.  Code
doesn't have all of the necessary error-checking and gabage collection, but it works.
Also, the colormap support hasn't been tested.