Removed SLICE_ALT from btree/operations.hpp.
Actually removed all of SLICE_ALT from operations.hpp.
Removed some of SLICE_ALT usage near the end of btree/operations.cc.
Removed SLICE_ALT from btree/get_distribution, btree/erase_range.
Removed SLICE_ALT from depth_first_traversal.
Removed SLICE_ALT from concurrent_traversal.
Removed SLICE_ALT from btree_store.cc through read (mostly).
Removed more SLICE_ALT in btree_store up to lock_sindex_queue.
Remove SLICE_ALT in btree_store.cc up to add_sindex.