Adds basic support for filtering games using tags that the user can set on account page
Add option --list-tags to list all the tags user has assigned
Add option --tag to filter games using the tags
Replace --update-check option with --updated and --notifications options
--updated restricts downloader to operate only on games that have update flag set in account page
--notifications shows the number of new forum replies, updates games, unread chat messages and pending friend requests
--clear-update-flags clears update notification flags for all games
Remove aliases for --game option
"free" could no longer be used as originally intended and "all" was unnecessary because leaving regex empty has the same effect
