ENG-4345 (partial) Agg Executor refactor. Small behavior change -- no longer requires COUNT(*) [or any agg] to take a dummy argument. Let the planner sweat it.
ENG-4345 (partial) Agg Planner tweaks, avoids IllegalCastException on expression of Agg, simplifies COUNT(*) handling -- no more dummy argument.
Revert accidental test tweak.
ENG-4345 Fixed major agg executor regressions, re-orged source files.
Merge branch 'master' into ENG-4345-aggexec
ENG-4345 Fix regression -- allocation error causing wrong answers (1 large group).
Merge pull request #396 from VoltDB/ENG-4345-aggexec

Eng 4345 aggexec