Probe all consoles, not just the first. It doesn't make a lot of

Probe all consoles, not just the first.  It doesn't make a lot of
difference, but might later on when we implement some sort of multi-head
console mode.  Select a console after probing them all.
Don't strdup a potentially NULL return from getenv().
If we don't select an active console, choose the first regardless.
Call the console init function, at startup time and on a manual change.
The env_setenv() function needs EV_VOLATILE because it's pointing to
data that isn't malloc'ed and will cause a fault if it's freed later.