This version adds the experimental SafetyManager system, which avoids faults like corrupted chunks & playerdata when the server is out of memory. It does so by safely shutting down the server and not allowing it to start up until the disk is empty enough for your server to function.
It is not set up by default, so it shouldn't cause issues if you don't want it to run.

Also, I've fixed a major issue where players weren't allowed to spawn in (log in) in chunks full of entities (in case the entity spawning was disabled via the chunk limiter). They wouldn't be able to chat/sleep/ or even be seen.

Thanks to the 2 people who found the bug out and managed to pinpoint the system that caused it:
@FixTheAdmin
@Ashinos