LitNode is a god object

[delbonis]

It does a lot of different things and there's a lot of implicit context being passed around between function calls as parts of the object itself.

In particular:

• Move channel management to some kind of ChanManager
• Move peer management to some kind of NetManager or PeerManager
• Create a FundsManager, possibly as a layer on top of the ChanManager and wallit
• Make things use the event bus ([WIP] Event bus system, replacing ad-hoc channel-based notification systems #326) where applicable

(I'll add more notes as I find them.)