This improves the diff performance by a factor of around 10. Things done
to do this are, among others:
* user String.replace(//g) instead of String.gsub(). It's
*much* faster
* Don't use anonymous inner functions for iteration, but instead
use for loops
* Don't use String.startsWith() if we can just compare a
single character
Because we are now so much faster, we can also show bigger diffs
by default.
Pieter de Bie