Add Biome Temperature Defining Value to Biome Customization

Issue description

Add a Biome Temperature Setting Value below the rainfall value to the Biome Customization menu

Placing this value below in code sets the biome temperature, a temp of 0.0F means cold with frozen water and Snow, 2.0F means a desert with no rain!

customProps.setTemperature(1.0F);

Issue comments

that would be right. the existing temps are just to say in what grouping of biome types the biome will spawn in. with what ellingtonisland suggested it would be possible to make your biome spawn with the desert and savanna but have the water constantly freezing.