Also fix a bug where the elaborator state wasn't updated on completing
the delayed elaborator, which could cause issues with implicitly bound
names in particular.
Need to run delayed elaborators before binding implicits, since there
might be some inside the delayed elaborator. Also reorganise TTC
implementations so they're all in one place.
Needs to be allowed to search for things indexed by pattern variables,
which are not really holes in the same sense, or it might not find
things in types.
(Aside: we're currently implicitly binding failed searches in types,
which is, I think, wrong... better to report the failure)
Don't build these until we've completed the whole clause (that is, don't
do it if we're inside a case block) because we might need to collect
more information to complete checking the case block. e.g. there may be
constraints inside the case block that are resolved outside.
It's just in the way, we don't use it for anything, and everything we
might get out of it we're already getting out of the type. Revisit later
if it turns out to be worth it.
If we store them on the type constructor, we're required to have the
construction available, which might not be the case when reloading ttcs,
because we load and process modules *before* things they import.
With the --yaffle flag, you get the old behaviour which is to invoke the
checker for the core theory (and all the tests are updated appropriately
for this).
This gives useful information for expression search, because we can add
lambdas while we're still building the environment, and start looking at
locals after that.
It turns out we need a new kind of map, mapping possibly ambiguous names
to values. This is what 'Context' does but we can only have one of them
because it resolves names to a position in an array and it'd be
confusing to have more than one index per name.
