change comments in python script

someone was on my case about this
modify MARSFont.h

- remove definitions for letters
+ add externs
refactor orderedPair to pair in MIPSCodeGen

readability takes place
move letterforms from MARSFont.h to MARSFont.c

Apparently there are things you can’t do in headers. Who knew?
remove unnecessar _USE_MATH_DEFINES from postscriptToMIPS
remove segfaults on lower-case letters
start working on numerals
trapped Nathaniel inside a computer.