Merge pull request #12 from bdrumheller/working

add, sub, or
Merge pull request #13 from tassiahmed/working

Working
Moved implementation of add and sub to addu and subu since they were the actual implemantations for those instructions.
Also added the func code for SUBU into sim.h
Merge pull request #14 from tassiahmed/working

Moved implementation of add and sub to addu and subu since they were the...
Added implementations for add and sub that check for overflow and break if overflow is detected
Merge pull request #15 from tassiahmed/working

Added implementations for add and sub that check for overflow and break ...
Added implementations and func codes for MULT, MULTU, DIV, and DIVU
Added the implementation of XOR BITWISE function and the FUNC code for it
Added the FUNC codes for the rest fo the R type implementations
Added implementation for the the rest of R-type instructions, although more clarification is needed for SRA and SRL as they do differ in
their operations bu I dont know how to account for that in C.
Merge pull request #16 from tassiahmed/working

Working
lw, sw, partial syscall