chore: Remove all obsolete code

[pandinocoder]

Description

All code with the Obsolete attribute should be removed (provided there are not extenuating circumstances preventing removal of something).

Since this will make updating directly to 0.9-beta not directly possible for all versions, we also need a upgrade version check and the final version of 0.8-beta needs to include code to re-save anything with Obsolete'd attributes in a format that 0.9-beta will be able to load.

0.9-beta and higher should refuse to upgrade from any version below the final 0.8-beta version.

Duplicate Check

• This task is not a duplicate to the best of my knowledge.