Alpha 13 RC 3: Now with actual moderate stability!

For this release every single module in the stable lineup has built successfully in the new Jenkins, and JoshariasSurvival seems good at least in the beginning, even the ShatteredPlanes world for it appears to work 👍

Probably the biggest change since last is the Gradle 6 upgrade merged to develop, which facilitated all the rebuilds. May of course still lead to as-of-yet undiscovered bugs as well

Also goes with an RC for v4 of our launcher: https://github.com/MovingBlocks/TerasologyLauncher/releases/tag/v4.0.0-rc.4 - which should be able to find this game zip at present!