Added additional I-types (everything but the last 2 branches i think).
Please Debug.
fixed mistakes and added test code
fixed more branching also fixed overflow check, which didn't make much sense seeing as it check if a 32 bit int had a value that didn't matter
some more code clearning and more testing
some more code clearning and more testing, but with the code saved this time
Merge pull request #7 from mllewellyn/rtype_alu_tests

Rtype alu tests