increment/decrement (C-a/C-x) had some buggy behavior where selections
could be offset incorrectly or the editor could panic with some edits
that changed the number of characters in a number or date. These stemmed
from the automatic jumping behavior which attempted to find the next
date or integer to increment. The jumping behavior also complicated the
code quite a bit and made the behavior somewhat difficult to predict
when using many cursors.
This change removes the automatic jumping behavior and only increments
or decrements when the full text in a range of a selection is a number
or date. This simplifies the code and fixes the panics and buggy
behaviors from changing the number of characters.
