Version 0.8 contains many small fixes (about 90 commits)

A lot of the fixes have breaking changes and because 0.7 was used for a demo at the show in Dresden on the devserver, I skipped from version 0.6 to 0.8 for the live version.

Because there is only one new feature and most fixes are non trivial bug fixes or refactoring for preparing upcoming features, there is no devlog this time.

Also that one new feature is a secret area, it doesn't make sense to write about it already.