Fixed i199

http://gsd.uwaterloo.ca:8888/question/867/add-attributed-feature-models-check
Added fold and map to traverse the IR
Merge from develop
Moved Ir traverse functions into IntClafer
removed unnecessary exports
Cleaned up implementation
Fixed small bugs from previous commit
Fixed bug where afm-check did not check for '*', added test file, and cleaned up implementation
Merge branch 'develop' into i199
Made foldMapIR consistent with iFoldMap
Fixed issue from previous commit
Merge pull request #28 from gsdlab/i199

I199