Allow taking list of input files on command line

[jordansissel]

Lev Gorenstein suggested allowing input files to be specified on the command line like you would with grep, awk, etc.

Proposal:

fex [extract1 extract2 ...] -- [file1 file2 ...]

The '--' exists to more easily separate extractions and file names (rather than making guesses "does this look like a filename?")

This will allow folks to do stuff like this:

fex [some extractions] -- /var/log/apache/access-2011*.log

without necessarily needing to do:

cat /var/log/apache/access-2011*.log | fex ...