Merge pull request #524 from JohannesPfeifer/master

Change unit test for H-matrix to be positive definite
test suite: add test file
Fix typo in field naming
Expand explanation of use_calibration optiom
Filters out error due to model being purely static.

First step in #526
Merge pull request #527 from JohannesPfeifer/bugfix_corr

Bugfixes for set_param_values and for purely static models
Fix typo in model_diagnostics.m