Loop detection could be done in message/term reference instead of pattern (?)

[Pike]

When looking at @spookylukey's evaluator, I noticed that the dirty-handling is done in pattern.

That's on a pretty hot code path.

Could we do that in message reference and term reference instead?

[stasm]

I added it in Pattern to make this possible:

open-foo = Open foo
    .accesskey = O
    .tooltip = Press {open-foo.accesskey} to open a Foo.

[Pike]

Right, it might be a bit trickier to get right. We'd need to keep open-foo, open-foo[var] and open-foo.bar distinct.

[spookylukey]

@Pike - and also remember the fallback logic that happens when some attributes/variants are missing. I believe I added tests for those conditions, perhaps only in my compiler branch.