Merge pull request #4 from stefankoegl/getpodcasts

CLI: extract _get_podcasts(url) convenience method
gpodder.coverart: Use util.update_file_safely when saving file
PEP8-ify the source
Merge pull request #6 from brot/f/pep8

PEP8-ify the source
Merge pull request #5 from gpodder/cover-art-saving

gpodder.coverart: Use util.update_file_safely when saving file
makefile: Add "make pep8" target to run pep8 with right arguments
gpodder.plugins.itunes: Add support for resolving iTunes feeds
gpodder.config: Move "youtube" to "plugins.youtube"
gpodder.registry: Central place to register plugin resolvers

This turns the YouTube and Vimeo plugins into real plugins, and
removes all cross-imports for them.
gpodder.model: Refactor fetcher usage now that it's stateless
gpo: Add new command "shortcuts" to list available URL shortcuts
gpodder.core: Remove prefix, as it's not used at the moment
gpo: Add detailed information in "gpo versioncheck" output
gpo: Add online help for all subcommands, update manpage
gpodder.util: Add itmss:// to the list HTTP schemes
CLI: search cmd to search podcasts on gpodder.net

requires Python 3 support of mygpoclient
(5058afa72ea9247e83caabaa7e6eb6025da2f493)