Evolve the rule for directory in ignore_files to be more natural
and easy to understand.
When a final '/' or '/$' is found we consider the pattern to match
a directory and the pattern is not modifed. In turns, is used, before
matching a directory's name a final '/' is appended to its name
before checking if it matches the pattern.
With the previous rule a final '/' in the pattern meant also a directory
but the '/' was removed from the pattern.
Francesco Abbate
7e9b2f30da