Turn off LocalOptimizationPass for the interpreter

* In this experimental way we are building expression trees,
  we build it very early in the pipeline and passes that modify
  instructions by combining instructions, moving operands from
  one instruction to another (as the LocalOptimizaionPass does)
  breaks the semantics of the tree in the current form it is
  represented.

* So, in the interest of experimenting to see how far this can be
  pushed, turning that off for now.
Less verbose toString for TemporaryLocalVariable