Merge branch 'release/1.9.0' into develop
cli: Whoops, forgot to actually apply some of the HDS options.
cli.argparser: Improve the number validation.
stream.segmented: Add support for multi-threaded segment downloading.

Resolves #338.
Update CHANGELOG.rst.
docs: Update dependencies.
win32: Update dependencies.
cli: Close currently running stream on keyboard interrupt.
plugins.hitbox: Add support for HLS videos.
docs: Add Slackware package to install page.
stream: Add some generic stream options.

These are generic options used by streams not covered by other options,
such as stream protocols specific to plugins, e.g. UStream.
Update CHANGELOG.rst.
docs: Add Ubuntu Utopic to install page.
docs: Add some info about multi-threaded streaming.
Added GoodGame.ru portal plugin
plugins.goodgame: Minor tweaks.

Also check if stream is available before adding it.
Merge pull request #466 from eltiren/develop

Added GoodGame.ru portal plugin
docs: Update plugin matrix.
Update CHANGELOG.rst.
travis: Remove pypy.