Tidied up bugs in Morris class

- Corrected error message so that the trigger matched the message
- Formatted a print command message to accompany error raised when
variables in group file do not match those in the parameter file
- Remove scale samples from morris_groups procedure in Morris class
Updated example morris usage
Added example for Morris groups
Added example for morris optimal
Added regression tests using Morris and Ishigami
Updated regressions to ignore optimal

(rtol set high)