The tests wasn't included in the last merged merge-request !52 (masking b),
because it was a complete rewrite from scratch, because !45 was outdated.

Masking b

See merge request !52

Data that is flagger.BAD is masked by default.
One can pass a flag or a list-like to the param to_mask to control the behavior.
Pass an empty list to disable masking.
Nevertheless IFF the index changed the masked data is not restored.
Also flags are NOT restored IFF they considered _flagged_ before the func call, but not afterwards anymore.
Also any data that is set on masked locations is not overwritten by unmasking.

Now giving an empty list to isFlagged return the correct result, an all-False series/dios.

    flagger.isFlagged(flag=[])

Before a nearly all-True data was returned, because of a call to notna(), that was not protected by the loop.

Patternrec

See merge request !50

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.