checking of keys in options file

[peisenha]

I suggest adding a check to the processing setup that ensures that all keys in the options file are meaningful for the specification of the user request. For example, we set 'n_types' in the options file and then were wondering what determines the number of types in the end as it can also be inferred from params. We got the following response from @tobiasraabe:

The number of types is always inferred from params. Setting "n_types" in the options will be overwritten.

[tobiasraabe]

#262 has reduced the amount of information in options. There are only seeds, number of draws, definitions of covariates, etc. left which are all validated in _validate_options if possible. . Thus, there should not be any confusion left. options are essentially read-only.