Fixes #449, stopping AllMembersSupplier hiding DataPoint method exceptions

Also includes a rewrite of the Theory nullsAccepted code, since that relied on the previous behaviour of this.
Added parameter to annotation to mark exceptions in datapoint methods as ignorable.
Failing single-datapoint methods keep their original stack trace
Merge branch 'master' into datapoints-exceptions-#449
Refactored out ignorable exception type-matching to minimise duplicating
of that logic
Merge pull request #639 from pimterry/datapoints-exceptions-#449

Fixes #449, stopping AllMembersSupplier & Theories hiding DataPoints method exceptions