Joimer/Pokemon-Showdown — pull request #2 by MJB47 (2013-02-17 18:05:42+00:00)
Title: Override rollMoveHit to add 1/256 miss chance

line 287 is the key line. essentially made it roll a random number up to 100.4
(100 + (1/256) such that there is an extra 0.4% chance to miss on all moves
except things that ignore the accuracy check (swift)