Add the possibility of having user-defined modules (not only plugins for existing modules)

Strengthening TAR signature.

ISO 9660 Boot Record and Primary Volume signatures, ref: http://wiki.…

Create extraction dir if it does not exists

Removed excessive size field validation for LZMA signatures; their compression is already validated, which is a better metric anyway.

Zip footer signature accurately reflects its size

Added a KGB archive signature.

adding MPEG transport stream signatures to magic/animations

Add signatures for qnx6fs & qnx ifs

several firmware magics

Update kwarg processing to ensure modules don't receive a mutable reference to defaults

Update kwarg processing to ensure modules don't receive a mutable reference to a class variable default. Fixes #207, also the Signature Modulemodule was leaking memory.