* Use strcspn to scan ahead for long regions of uninteresting text in string handling (performance).
* Remove cruft specific to my system in phpTest.php.
* Remove a test that was in incorrect syntax, and useless without adding variable support.
I've made it more performant and fixed a few bugs by using regexes
instead of PHP loops, where possible, under the assumption that the
PCRE parser is more efficient than the same thing implemented in pure PHP.
Also, I'm now passing the same string around and calculating offsets, which
Tim tells me is far more performant than continually truncating the same string.
All tests still pass, with the exception of string.t, which I've modified
to remove the offending code, which never worked.