Rustling Leaves

Added

• Seasons with Serene Seasons: in autumn many more leaves fall and more and more of them turn yellow, orange and red, until by late autumn nearly every falling leaf does; in winter hardly a leaf falls (the litter on the ground stays); in spring only a few leaves fall, while blooming cherry trees shed a few more petals; summer stays as before. Leaf fall changes gradually through the sub-seasons. Biomes and dimensions without seasons (tropical biomes, dimensions not whitelisted in Serene Seasons) are not affected.
• New client config section seasons: turn the season effect off, or set how many leaves fall in late autumn and in winter and how strongly the autumn colors grow. These multiply the existing fall rate and autumn color options.