Make 'make tests' a synonym for 'make test'

I keep making this mistake and when you bang your head against the wall
often enough, it's time to remove the wall.
sinksmtp: overhaul what arguments we have, throwing a bunch out

Sinksmtp now takes two rules files because that's what I want (a core
one and then a supplemental one, so I can leave the core one alone and
usually only edit the supplemental one to fiddle with wacky things).
I took out a pile of options that I don't use and some that are better
done in the core rule file. There will probably be more changes.
sinksmtp: sneakily mark the host as being optional in the 'host:port' arguments

Because it is; this is the standard Go network address parsing behavior.