Add --precompiled option to Python interpreter

This enables manual tweaking (e.g. instrumentation) of the compiled output
before running the program.
Silence warning
Revise primitive data handling

Eliminate most of the "normalized term" flavor in favor of DPrimData.
Change DOpAMine to use OPAsn[PV] pervasively, rather than OPAsgn.
  This should give us cleaner separation between the pretty-printing
  we use for debugging and the syntactic forms required by the codegen.