merge parametrization (with multiscaling and flattening) into master, which had minor bugfixes in the meantime (aggregation function and likelihood sign)

Merge branch 'parametrization' into development

finished adding eta2 to all functions. some minor checks are still missing. also readme shows bad diagnosis plots (worse than with only tau)

finished adding tau parameter to all functions. all parameters are allways stored in fit (except in fit) .also created IDF.plot.fit() (but it is very slow)

Development

See merge request Rpackages/IDF!6