Fix bug in bm.pm about localizing $_.
Avoid error when ^D is entered for passphrase.
Decode @ARGV earlier.
Set default gpg filter unless --pgp option provided.
Move color staff to Colorize.pm
Update module handling.

Now -M option can be used in .greplerc or module definition.
Skipping device file seems to be unnecessary.

This is especially not to skip /dev/null.
Introduce --pf option for post-process. (closes #1)

-Mical --detail did not worked due to the modified behavior of
--of option which is now invoked for each file output.
Post-process filter is invoked just once at the beginning.
Moved --of option handling not to exec command with empty output.