Ignore descriptive annotations during inversion

[michaelmior]

Some keywords such as title do not have any impact on validation, so don't have a meaningful inverse.
This skips some of these keywords during inversion.

[otto-ifak]

@michaelmior Thank you very much for your PR! You can pass a NormalizationConfig to the normalize function now, which contains an attribute discard_fields. Here I added - among some others - the annotation keywords you mention in your code.
(see commit 891564b)

[michaelmior]

@otto-ifak Thanks!