[darcs patch] filepath: normalise trailing dot

Hi, the attached darcs patch modifies the behaviour of normalise to handle trailing dots in a path. The previous behaviour yielded this: Prelude System.FilePath> normalise "../." "../." Prelude System.FilePath> normalise ".././" ".././" Prelude System.FilePath> normalise ".././.." "../.." This patch modifies dropDots such that the check for (".":[]) only occurs once for the path, after which a driver function dropDots' is used which skips this check. Hence "." can be removed from the end of a longer path, but a path of just "." is unchanged. (my trac account is pending verification, I'll reply with a trac ticket # later if needed) cheers, Conrad.