Update Biomes_O_Plenty Texture File Structure 

Updated the current textures to use the new file name format. Also
renamed textures to the new names of the blocks. I have tested these
textures and they are all working.

New Texture Format:
Leaves = leaves_{name}_fancy/fast
Log = log_{name}_side
Log Heart = log_{name}_heart
Plank = plank_{name}
Saplings = sapling_{name}