Specify absolute fee max instead of average fee max

Right now it seems that it’s only possible to specify the maximum average fee per hop for a rebalancing route, when really I’d be more interested in specifying a maximum absolute fee (still in terms of the lnd default for a single hop). Basically, I’d rather pay 100 satoshis for 2 hops than 120 satoshis for 3 hops, even though the latter has a lower per-hop average.

This could also allow for some shortcuts to prevent searching for routes when the fees for the first or last hop (specified by the -f and -t arguments) exceed the maximum fee. If I don’t want to pay more than 10 times the lnd default fee, and I’m trying to rebalance a channel which itself charges 20 times the lnd default fee, then the rebalancing should not even be attempted potentially saving time and headache. I guess this might change if negative fees ever become a thing, however.

Last minor request, it’d be nice to have a single character alias for this argument, like -m or -f instead of --max-fee-factor.

[C-Otto]

It make make sense to specify the fee limit as a ppm value.

[C-Otto]

QueryRoutesRequest accepts a fee limit, which in turn can be configured with a fixed fee, or a percentage of the forwarded amount.