according the WIKI, rainfall valuemust be at least 500 for fruit trees

minimal... but seams to be a problem: http://terrafirmacraft.com/f/topic/7168-no-fruit-trees-at-all/

but there is still the question if it would be better to change the WIKI and leave the code as is (eventually adjusting WorldGenCustomFruitTree where it actually is ">= 500")?