Added Min-Weight Improvement For Regions
Added Min-Weight Improvement For Regions

This essentially means that we can specify a minimum weight, so that we
will only create regions that get us at least that many bits of
improvement. Currently set to 5.

jackfirth/herbie,jackfirth/herbie,jackfirth/herbie,jackfirth/herbie,jackfirth/herbie,jackfirth/herbie