Call trace information in exceptions

[Idorobots]

It would really ease up debugging if the current continuation also contained a call trace up to that point - each &apply invocation should extend it with the closure metadata, while each scope exitting continuation automatically removes the topmost value.

[Idorobots]

A faster solution is to keep a ring buffer of recent call frames in memory - &apply then just pushes a frame into the call trace and then executes it.