Added a hook to disable tile permutation in expression evaluation.
Minor fixes and reorganization to expression printing.
Changed the scope of some typedef in expression objects.
Changed the typedefs in ScalAdd and ScalSubt to be consistent with non-scaling versions.
Added a missing semicolon to a ScalTsr typedef.
Fixed distributed eval type in Tsr::make_shape.
Added a default constructor, assignment operator, and map_pmap function to ProcGrid.