To make the "Payments" category a bit less overloaded and to move the
Mission Control configuration commands away from the "root" category, we
create the new "Mission Control" category that we move the commands
into. We do this in a single commit so the next one where we move them
into the same file can be a pure code move without any additional
changes.
Probabilities are no longer returned for querymc calls. To still provide
some insight into the mission control internals, this commit adds a new
rpc that calculates a success probability estimate for a specific node
pair and amount.
