Add closure binding's tracking to name resolution

Add closure binding's tracking to name resolution

When we have a closure block referencing variables in a parent function,
we must track what these are. We do this by having a context of closures
so if we have a variable reference and its declared in a rib whose node id
is less than the node id of the closure's node id we know it must be a
captured variable. We also need to iterate all possible closure contexts
as we might be in the case of a nested closure.

Addresses #195