fix perms on rest source
support slow loading synonyms to MongoDB
synonym load; annotate heavy I/O section

This is a great candidate for applying a threaded approach to decrease
the amount of time it takes to load synonym data.
relocate mongo-check main to subdir
bump MongoDB indexes in nsvalues
defer write-heavy I/O to a couple threads
go.sh; swap load/check order
mongo-check.sh; use mongo_check subdir
synonym load; one thread is fine
README.rst; license
bump README.rst