This is best-practice (to ensure prototypes match up), but there were a
few places we didn't (at least, directly). Make it a requirement,
either of form "foo.h" or <dir/foo.h>.
The noise is the change to our print templates.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Also, we split the more sophisticated json_add helpers to avoid pulling in
everything into lightning-cli, and unify the routines to print struct
short_channel_id (it's ':', not '/' too).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>