Fix bring_sindexes_up_to_date
Distinguish between major and small erase_range operations. Implemented rdb_erase_small_range().
This should fix #1885.
Make sindex post construction not detach nor delete blocks. Made sindex post construction yield more reliably.
Merge branch 'next' into daniel_2073
Pass deleter all the way through for sindex updates.
Also use noop deleter in post_construct_traversal_helper.
Use noop deleter when cleaning secondary indexes if they haven't gone through post construction yet.
Pass deletion_context_t's to make detaching/deletion work properly. Fix detaching problem when dropping incomplete sindexes. Make btree splits detach values.
Style fix.
Merging now also detaches values. Just leveling is left.
Fixed a memory allocation problem.
Leveling now detaches values as well.
Two missing detach cases.
Proper detaching of btree nodes during balancing operations.
Fixes leaf::level() moved values return value.
A little refactoring and addressed defects.
Merge branch 'daniel_2073' into next

Conflicts:
	src/rdb_protocol/btree.cc