Fixed r.literal in update.
fixed replace regression
added tests
Removed coro_t::spawn()
Merge branch 'daniel_no_spawn' into next
Merge branch '1839_fix_update_literal' into next
Merge branch '1570_fix_replace_regression' into next
adding stats recording for backfills, sindex post-construction, and range gets
adding stats for number of running query language ops per machine
Merge branch 'next' into sam_alt

Conflicts:
	src/arch/runtime/coroutines.hpp
	src/rdb_protocol/btree.cc