Reduced the complexity of typedef in Expr::make_array().
ScalMultContEngine now only inherits from ContEngine.
Corrected the this class typedef.
ScalMultContEngine::init_vars() no longer tries to call nonexistent left and right member functions of BinaryEngine.
Added missing ScalMultContEngine::init_vars() member function.
ScalMultContEngine::init_dist now uses the correct parameter.
ScalSubt tile operations now have non-const parameters for consumable arguments.
Added some preliminary implementation for expression test cases.