stack traces should give better location on non-tail frames #84
Description
The context includes the return-context functions, but those functions don't currently remember where they originated in the original source. We should add those in, so that even in the case where we're not running under traced-app we can still get good stack traces. It'll also reduce traffic on the continuation marks.
Basically, we'd like to special-case function application in the context of a with-cont-marks using our special traced-app key.