Fix overzealous legacy code removal from torrentmanager
Fix some typos in my previous commits
Fix 2247: AttributeError in deluge.error.DaemonRunningError

* Removed all the properties in error.py and added more tests
* Handle failure in client.py handling RPC_ERROR (From older daemons)
Speedup in tracker_error_filter
Cache items in get_filter_tree
Added some tests for rpcserver
Fix bug introduced in 19234d