[#2335] [GTKUI] Fix startup failing with 'cannot acquire lock'

This issue was caused by an unclean shutdown of Deluge, usually on system shutdown, and upon rebooting
the PID stored in the lockfile is in used by another process thus the lockfile is never removed. It
affects users with Deluge set in startup applications as the PIDs are more likely to be reused.

 * Lockfile is removed if Deluge is restarted in IPC.
 * Renamed the old_tempfile variable to make it clearer as to it's role.
Update copyright year in About dialog
Added TorrentTrackerStatusChangedEvent
Added ClientDisconnectedEvent
Major changes to how torrent updates between daemon/client

This changes how torrent updates are sent to clients as well as
improvements to the ui update routines to make it faster. The
clients can now ask for only the updated torrents being sent,
which makes it possible to only update the necessary torrents in the UI.

* GTKUI now asks only for changed torrents
* Added torrentfilter.py to sessionproxy which handles filtering
* Added PyDBLite (wtih SQLite support) too filtermanager.py and torrentfilter.py
* Added tests to deluge/filterdb/DelugeDB.py
Implemented show ownership option in GTKUI
Fixed webui according to new core.get_torrents_status changes and implemented quick search field