starting patterson implementation. About to merge with Filipe's new code for the fitting interface.
Merge branch 'devel' of github.com:FilipeMaia/owl into devel
Now the data of tags and model parameters are organised in separate classes. This also reduces redundency (before tags were created for every dataItem, now this is done only for every group items). I might have fixed the bug corrupting h5 files when saving tags. I avoid deleting datasets, I remember that this caused problems before in a different application. But as the bug was not reproducible I am not so certain about my fix.