Allow 2+ BCP to be selected.

Keyboard arrow keys now effect the position of all selected BCP.
multi bcp, can now drag and alternate to alt+arrow keys to move corner
 points ok, other types need
 love.
come cleanups
cleanup!
docs++;
Merge pull request #675 from monkeyiq/2013aug/multibcp1

Rudimentary support for selecting 2+ BCP and operating on them all