#59 Add @check and @mpicheck annotations

[Tom Clune]

When a test uses a helper procedure that potentially throws an exception, it would be useful to have an annotation in the driver procedure that checks if exceptions were thrown and issues a return if so.

Essentially @check expands to if (any_exceptions()) return.

Note 1: not committed to the actual spelling of this annotation
Note 2: possibly use @try @catch instead or in addition to.