1.Small modification in how we handle CallExpr in TypeChecker & EffectChecker.
2.Removed the encounteredFatalError method from TypeChecker & EffectChecker,
  since it is actually already provided by the base class.
3.Minor Documentation Improvements
Adding skeleton of pass that will check non-interference.
(The previous commit accidentally included the updates to
SafeParallelismChecker.cpp to invoke this pass.)
Adding class SpecificNIChecker to check with each type of parallelism introduced
by an API call (to support at first the TBB parallelism),
Also, refactored VisitorBundle to make it a static member of asap::SymbolTable
thus reducing the arguments that need to be passed around.