* Use dogpile.cache sha1_mangle_key to mangle cache keys
When using the subtitle hashes as cache keys, sometimes they come
out as filenames of 270 characters.
Not a lot of filesystems out there support filenames with over 250
characters.
This behaviour was reported with ext4 and zfs on both linux and FreeBSD.
The dogpile.cache utils come with a function that returns a hex digest
of the key, limiting the filename to a fixed length of 40 characters.
* Set region to subliminal.region and only then configure it, instead of assigning the result of configure to the property
* Make sure subliminal ALWAYS mangles keys with the sha1 to prevent filenames that are too long