#18 Room, Thing, and Exit parents

[Greg Taylor]

It'd be great if there were mux config directives that
would allow rooms, things, and exits to be set to certain
default parents upon creation. Rhost does this and I'm
sure other codebases too, and in our case we have
these annoying room parents that are a necessity due
to mechs.

I guess the best way to keep it from bugging anyone
who doesn't like this would be to ignore the config
directives if they don't exist or are a negative number.