Signed-off-by: Simon Lipp <laiquo@hwold.net>

flake8 --select W391,E302,E301,E304

autopep8 can't fix W391 even though it claims it can.
Fixed using a simple custom script.

Modules can raise this exception when they want to print errors to user

As discussed on IRC, those huge constructors aren't ideal.
Includes misc pep8 fixes.

This allowed to fix a crash when parsing descriptions with invalid
unicode (KickAss is quite horrible it seems).

A new attribute, filename, has been added. It is the recommended
filename of the .torrent file, and should simplify downloading files when
it will be supported by weboorents.

The usage text/tail was useless, lxml supports text_content() for HTML,
which is much simpler.