* Skip forced arguments in conversion check
This isn't always safe - we have to have also checked the type of the
things we're converting - but in the place where it is safe it can be a
pretty significant saving.
* Use Closures, not NF, in Binders for normal forms
This means we don't need to reduce argument types during unification if
we don't need to. Also, we now try to avoid reducing closures during
unification if they are unified with a metavariable. Together, this
saves a huge amount of unnecessary evaluation in programs that do a lot
of compile time evaluation.
* Didn't mean to update idris2api.ipkg
* Fix dodgy merge
Local hints need to reduce (just like global hints do) so we expand
their definition to the lifted name before applying them.
We're identifying the global hints by knowing that the binder name is a
nested function name. This is a bit of hack, and it'd probably be better
to record that information in the binder instead, but that's a more
substantial change than I want to do right now.
