Clientside prediction and rollback, navigation disabled

This release splits the server into a separate project so development on the simulation can continue while the server is running.
This release adds a first prototype for clientside prediction and rollback. The client runs the simulation with local commands. If remote input arrives, the simulation will roll back to the remote frame and fast forwards with the new input to the last local frame. Rollback only works for spawning entities so far, navigation feature is therefore disabled and will come back in the next release.