ADDED monoGratingAngleStatus monitor
and generalized ```onMonoMirrorAngleError()``` to
```onMonoAngleError()``` to handle errors from either motor.
Merge pull request #791 from acquaman/Issue784

Pull Request for Issue 784 - Adeded REIXS monoGratingAngleStatus monitoring

If @epengr is happy, then I'm happy. Looks like it only impacts REIXS in the end.