Added a (get-frame) function in order to allow for accessing a frame
in a closure.  With this, the frame can be captured and
reused from a closure with (exec-in-frame captured-frame code-block).

I belieave it may be more flexible than continuations..

NOTE:  I think the side effects will be minimal as anyone doing
this must do it on purpose.  There is not accidental way to use
this feature.