Update 1.16

- Update to the staff menu UI
- Allow text search in the items menu to make it easier to find items
- Bug fixes for 1.15
- Fix timezone-related crash on startup, which affected some machines with Eastern locales (e.g. Korean, Chinese)
- Fix random crash on some machines caused by use of a previously-experimental graphics multithreading setting
- Fix other very rare instances of crashes in Unity engine
- Reduce framerate spikes when creating new characters and parts of GUI during gameplay