In the Min. Cost Flow solver we put a constraint on arcs capacities,
such that the total flow that can be allocated through a channel does
not exceed htlc_max. This solves two previous problem of the htlc_max
constraint at the MCF level.
Any file in this directory which is executable and whose name only
consists of alphanumeric characters, space, '.', '-' or '_' will be
automatically loaded when lightningd starts (unless suppressed with
commandline options).