adjust contour to track edit sequences better

Specifically when there is no delegate and an edit
sequence is started, track that differently in case
a delegate is set before the edit sequence ends
(in which case we don't want to end the edit
sequence in the delegate since we didn't start it
there)

related to PR 13491
fix bug in check syntax introduced when adding the
new green, mouse-over, which-identifiers-are-the-same bubbles
Rackety
make #:keywords have different color prefs in DrRacket

closes PR 13492