v1.7.0

As the community rallies for our biggest challenge yet, our promotional team started spreading Marshallton 2021 posters throughout our dancing venue!

- Updated world to Unity 2019.

- Optimised all mirrors for improved performance.

- Added new "Avatar Brightness" setting which allows you to locally set the brightness of all avatars.

- Improved UI performance.

- Optimised files to further reduce downloadsize.

- @Chatmans added Marshallthon posters throughout the world, design by @Evelien#3865 !

- Updated credits and Patreon bench.

The Unity 2019 engine upgrade can cause some unexpected issues so there might be some instability in the following weeks.