Remove useless trailing \
Remove trailing spaces
Add missing empty lines

autopep8 -ir -j2 --select=E301,E302,E502,W291,W293,W391 .

Diff quickly checked.

autopep8 -ir -j2 --select=E303,E125
Diff checked manually.

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.