Refs Tokutek/ft-engine/#40 Add c_restrict_to_range function to force cursor to keep track of prelocked range
Refs Tokutek/ft-engine#40 Rename c_restrict_to_range to c_set_bounds, delete c_pre_acquire_range_lock
Refs trac 6712, Refs Tokutek/ft-engine#40 Reduce computation time when we read something out of bounds (do not look in other basement/leaf nodes)
Refs trac [t:6712], Refs Tokutek/ft-engine#40 When possible, optimize by only checking left or right bound during a bounded query
Merge branch '6712' into releases/tokudb-7.0