Latest Shift

0.8.4 - Hot air, visible again

- Balloon envelopes once again show the hot air filling them up with shaders enabled (fills top-down as burners heat; re-rendered through a shader-safe path)
- Burners show a flame again with shaders enabled
- Without shaders, the original fancier effects are restored (they had been disabled for everyone in 0.8.1/0.8.3)
- Levitite on airships stays plain-but-stable under shaders for now - the full shimmer needs a fix in the upstream rendering library