Fix the sizing of the scratch file buffer so that it works regardless of what
layout you have to start.
Fix a bug in the scratch buffer where newlines were not being properly
added. This was because something became a float in ST3 that used to
be an int and we were trying to do modulus of a float.

This change also allows the user to delete from within the middle of a
path but it's probably not terribly useful in the current incarnation.