We had enum channel_side (OURS, THEIRS) for which end of a channel we
had, and htlc_side (LOCAL, REMOTE) for who proposed the HTLC.
Combine these both into simply "enum side".
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
I originally overloaded struct htlc for this, as they go through the
same states, but separating them turned out to be clearer.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
