(13 Dec 2019, @ankostis): ChainMap Solution for Rewrites, stable TOPOLOGICAL sort

• FIX(NET): TOPOLOGICALLY-sort now break ties respecting operations insertion order.

• ENH(NET): new :class:.Solution class to collect all computation values,
  based on a :class:collections.ChainMap to distinguish outputs per operation executed:

  • ENH(NETOP): compute() return :class:.Solution, consolidating:

    • :term:overwrites,
    • executed operations, and
    • the generating :term:plan.

  • drop(net): _PinInstruction class is not needed.

  • drop(netop): overwrites_collector parameter; now in :meth:.Solution.overwrites().

  • ENH(plot): Solution is also a :class:.Plotter; e.g. use ``sol.plot(...)```.

• DROP(plot): executed arg from plotting; now embeded in solution.

• ENH(PLOT.jupyter,doc): allow to set jupyter graph-styling selectively;
  fix instructions for jupyter cell-resizing.

• fix(plan): time-keeping worked only for sequential execution, not parallel.
  Refactor it to happen centrally.

• enh(NET,.TC): Add PREDICATE argument also for compile().

• FEAT(DOC): add GLOSSARY as new :ref:arch section, linked from API HEADERS.