Only store actual lifetimes.

Don't add the non-lifetimes of automata that don't specify them to our list of unique lifetimes.
Add some lifetime debug output.
Automaton::Lifetime::operator==() can be const.
Compare protobufs, not protobuf pointers!
GAH! Return false if *not* equal!
Add Automaton::Lifetime::String().
Assert that we added the correct thing.
Fix incorrect use of sunrise/sunset names.

This is apparently what I get for committing code at 2am.
Finally rename tesla_*_context -> sunrise,sunset.

These mightn't be the best possible names, but at least they're consistently-used now.