RootObject field name for ContentType

[koeaw]

Loosely related to #79 (not conceptionally but would require same type of change):

I had a look at 7ef186b only due to recent (now-resolved) conflicts and got confused because the commit message doesn't seem to square with the changes. The changes decrease readability (PEP8, consistency between variables) but were said to be made to conform to Django standards.

Unless I'm getting things confused here (and this is about something different?), the Django docs recommend the spelling content_type for a field used to reference a model's ContentType. I would thus suggest to revert the field name, or better, to stick to the docs, i.e. drop the self_ prefix and use just content_type.

Note this isn't me trying to be nitpicky but wanting us to avoid changes for the worse (if not actively working toward changes for the better).

[sennierer]

seems we have both versions in place contenttype and content_type. We should decide for one

[b1rger]

FTR: waiting for the old relation implementation to get dropped, then we might even be able to drop the field alltogether