Merge branches 'devAST' and 'master' into devAST
added checks for NULL pointers
Merge branch 'devAST' of https://github.com/Torwegia/cs660 into devAST
code needs to be fixed
added ast.h
added reverseAST.h
added reverse AST cpp file
Merge branches 'master' and 'devAST'
removed separate cpp files
Merge branches 'master' and 'devAST'
Merge branch 'master' of https://github.com/Torwegia/cs660