Update notes for 29th May

Added new erosion speed with configurable value
Added configuration setting for whether sea level changes the temperature
Added configuration setting for whether ocean water rises when editing land under it
Fixed serious performance issues on Nvidia cards introduced in previous update
Overall simulation ~10% better performance, much better performance when zoomed in on trees
Minecraft exports now feature water with fractional heights
Fixed exporting Minecraft worlds with custom sea levels
Fixed rendering issue with topographic and other data overlays at map edges
Fixed behaviour on map edges where dirt would form a barrier
Temperature map now properly updates when game is paused and at game start
Fixed dirt/sand display on map load when paused
Fixed bug with sea levels above 0m not saving/loading properly
Fixed bug with shrubs not appearing when sea levels are lowered
Fixed bug with cold rocks rendering differently to warm ones
Fixed sand and dirt coverage in Minecraft export
Fixed grass coverage in Minecraft export
Fixed bug with water disappearing after earthquake
Limited ice height to prevent buggy behaviour
Fixed heightmap export when image dimensions are lower than world dimensions
Fixed bug with earthquake arrows direction when slip is negative
Fixed bug with ocean water heights not being saved/loaded properlyn