In this commit we use stringSlice flag for incoming and outgoing
channel ids args, for forwarding history command. The Int64Slice
range does not cover all possible scids in the custom alias range.
This commit adds incoming and outgoing channel ids filter to forwarding history request to filter events received/forwarded from/to a particular channel
Adds --route_hints flag to sendpayment.
Hints should be JSON encoded (see usage for example).
Adds --route_hints flag to queryroutes.
Errors if blinded paths are set.
We only append the chan_id and the human readable scid
for the commands `listchannels` and `closedchannels`. This
ensures that other commands like `buildroute` are not affected
by this change so their output can be piped into other cmds.
For some cmds it is not very practical to replace the json output
because we might pipe it into other commands. For example when
creating the route we want to pipe the result of buildroute into
sendtoRoute.
We want to export some of our CLI code to re-use in other projects. But
in Golang you cannot import code from a `main` package.
So we need to move the actual code into its own package and only have
the `func main()` in the `main` package.
