Add a new ACE for Set timestep, 3 modes:

• Default (1/60) per C3 tick
• Fixed (set to a particular value, default is 0.0166 ~ 1/60 same as default) per C3 tick
• Adaptive - use the last C3 dt value per C3 tick (could help with higher refresh monitors, please give feedback)

I also changed how some of the libraries are included. The comlink lib (communication between rapier worker and main thread) is now included inline, so export will also work. The rapier lib is currently downloaded from a NPM CDN link, so takes some time to start, be aware of this. In production, include a loading layout, etc. to allow time for this script to load and start running.