This module provides a convenient way to perform cleanup or other forms
of resource management at the end of a scope. It is particularly useful
when dealing with exceptions: the Scope::Guard constructor takes a
reference to a subroutine that is guaranteed to be called even if the
thread of execution is aborted prematurely. This effectively allows
lexically-scoped "promises" to be made that are automatically honoured
by perl's garbage collector.
ok jasper@, tested by espie@
4debab46fc