New memcpy()-based wordwrap() implementation. The simple case

New memcpy()-based wordwrap() implementation. The simple case
(single-character break, no forced break) appears to be about 60%
faster, and there's simply no comparison for non-simple cases with
non-trivial amounts of text. The old algorithm was O(n^2) (with an
unfortunately large constant factor) because of the use of strncat(),
the new one is O(n). Added some more tests, too.
@ - Made wordwrap() significantly faster. (Jim)
# test case: $t = join('',file('ChangeLog')); $w = wordwrap($t,10,"\n",1);
# new code completes in less than a second. i'm still waiting for the
# old code to finish.