needforspeed: use "fastsearch" for count and findstring helpers. this

needforspeed: use "fastsearch" for count and findstring helpers.  this
results in a 2.5x speedup on the stringbench count tests, and a 20x (!)
speedup on the stringbench search/find/contains test, compared to 2.5a2.

for more on the algorithm, see:

    http://effbot.org/zone/stringlib.htm

if you get weird results, you can disable the new algoritm by undefining
USE_FAST in Objects/unicodeobject.c.

enjoy /F