Unwinding

Unwinding is used at run time in 11 crates (of which 11 optionally). It is a direct run-time dependency in 3 crates.

Depender (with downloads and own rev deps)			Unwinding version
4.1K	1	semihosting	optional	^0.2
600	3	origin		^0.2.0
500	1	c-scape		^0.2.0