Add proper GPLv3 license notice

The main file previously only contained a very short license notice.
Add the full paragraph recommended by the GPLv3.

Update the version/modification date and add my own copyright notice.
Add SHA1 calculation and output
Rename main script

As the script now calculates both the CRC and SHA1 of the input files,
rename it to reflect its generality and abstraction from anime files.
Add support for passing folders as args

Previously, the script could only take actual files as input arguments.
Expand it to handle directories by processing all files on the first
level within that directory (i.e. non-recursive) at the moment
(functionality for recursive handling is present but untested and
cannot be enabled via commandline option at this time).
Add SQLite3 support (read-check)

Remove version number (they don't currently make sense as there is no
plan for development; Git revisions should suffice).

Add encoding line to tell Python about the UTF-8 nature of the main
script file.