v2.0.3: MD5 hashing support for existing files

- Implemented checking of existing files with the MD5 sum (Using
Webworkers to do the work in the background) if they match, the file is
disabled
- Recheck files button was added to allow you to recheck the files such
as when you change the folder name, change the title field, or rename
the files
- Added option to disable the automatic checking of existing files, you
can check the files at anytime by clicking the "Recheck Files" button
- Tweaked the regex to match more boards