A better version of the 'z_cleanup' test has been integrated into Bessere Tests in the latest commit (as of writing this commit message). Therefore this test is no longer required as Bessere Tests will warn us on shutdown for any leftover children or orphan nodes from now on.
Changes in this commit include:
- Add Core.cleanup() and CoreBaseModule._cleanup() functions
- All builtin modules now clean and free any nodes
- Reduce code duplication in src/core.gd by not writing the same code for all builtin modules but instead iterating through a array
