Merge torclient/torrelay/torbridge/etc into one Tor component

Nick has been asking for a long time now for us to make a single Tor component, and use keywords to mark them as TorClient, TorBridge, etc. Using different components to describe what sort of Tor category a ticket is for drives him nuts.

Roger and Robert were pushing back because trac's search feature is abysmal, and our way of finding a ticket was to guess its Tor component and then look at the list of tickets under that component. But we should be able to do the same thing just narrowing by keyword.

Ultimately, since Nick is the primary user of this component, I think it makes the most sense to let him pick the conventions.