Fixed i226

http://gsd.uwaterloo.ca:8888/question/948/unary-minus-generated-incorrectly-for-alloy42
Merge branch 'develop' into i226
Merge branch 'develop' into i226
added a test case for i226
Merge pull request #25 from gsdlab/i226

Fixed i226
Removed extra test file and switch order for (-1) when given an unary minus
Merge branch 'develop' into i199