Add a license.
Indent the code.
Add includes for external functions.
Improve function prototypes.
Start adding the correct type to things that are pointers.
Start fixing compiler warnings.
Instead of directly executing the compiled code (which only works on x86 Linux),
write the internal compiler state to stdout. This makes it easier to test whether
or not our refactoring is breaking anything.
Return a zero status on success.
Add error checking for a missing input file.
