Added fllog2near
Added fast-flfsa/error and flfsa/error (fused square-and-add)
Altered `keymap%` to not claim to handle key events that it doesn't

Previously, `keymap%` would return #t for all shift, ctrl, and key release
events. DrRacket's editors would then not handle those events (correctly,
as they shouldn't handle already-handled events), meaning that the events
weren't sent to any snips.