Leaf Litter Critters

initial release with the following features:

• animated woodlice, ladybirds, worms, shieldbugs, froghoppers and millipede particles that spawn in leaf litter
• yellow flat-footed flies spawn in leaf litter in dappled forests 26.3+
• only woodlice spawn in leaf litter in pale gardens
• biome-specific critter rarities in forests, dark forests and wooded badlands
• particles are spawned ambiently, by walking on leaf litter or by breaking it, all with different lifetimes and spawn counts
• config provided by khazodacore