Updated CRC Capture Regex

It's now looking for 8 hexadecimal digits surrounded by either () or []
or actually because of how it works (] or [) are fine too but users have
no incentive to name their own files somethign that stupid. This should
avoid the problem I had with Kyolug Returns, but may not actually be any
better overall.
Added CRC Override flag

The regex to find the CRC in a filename has been simplified
significantly.

It also is no longer the only way to get a CRC into the metadata short
of manually opening the site and editing, as you can pass whatever you
want via the -c flag, and call it a day. I'm assuming nyaa doesn't
actually validate that these CRCs are even valid four byte hex
representations, so if the user wishes to feed garbage I'm not going to
stop them.
Merge branch 'crc-override' into develop

Adds the ability to override the detected CRC from the CLI. This is
useful if the CRC isn't actually in the filename, or you know from
experience that the regex that I'm using to seek it doesn't actually
work for you.