closes #66, have may_table_be_empty call use the same transaction that opens and possibly creates the table, otherwise it may block behind that transaction's lock tree locks

Refs Tokutek/ft-engine#40 Rename c_restrict_to_range to c_set_bounds, delete c_pre_acquire_range_lock

Refs Tokutek/ft-engine/#40 Use c_restrict_to_range function to force cursor to keep track of prelocked range