don't implicitly downcast tagset_size()

Changes fileformat version for saved tagsets
formatting only; astyle -A10 lib/counting.{cc,hh}
more downcast removal; scope reduction; prefix oper
force 64bit-only builds on OSX
FORMATTING ONLY: astyle -A10
two more downcasts
Merge pull request #339 from ged-lab/fix/nodowncast2

Fix/nodowncast2