seems to be hard to stick to naming conventions

`write_back` parameter in `getResult`. While the previous
version worked in the sense, that it allowed to `save` computations
already done, I disliked the state-changing behaviour of that
implemetation. Now we have a way to realize the registered
test functions into a new `SaQC` without modifying the old one and
don't violate the functional interface of the `SaQC`-Objects
any more.

the actually needed charactersitics. The old check was forcing equal
columns on `flagger.flags` and `data`, a condition we don't need to
be satisfied and don't satisfy during the lifetime of `SaQC`-Object
either. The new check only guarantees, that all columns in `data`
have a counterpart in `flagger.flags` but allow the latter to have
additional columns as well.

Dataprocessing features

See merge request !49