Revert "Move the database core out of this repo."

This reverts commit ee25bd9ab172e8a39c4c3d290f7a90326afb8232.

That was a bad idea that'd only lead to development hell.
Revert "Move bullshit into a separate repository."

This reverts commit a967e2dc2fc6acd3ba96beee51db92f88b216d8a.