Fix/balance big trees

Been farming big (a.k.a. "Old Growth" in case of spruce/pine) 2x2-sapling trees - these are a source of a lot of wood, but seem to take as much time to grow as all other trees (despite logically and game-wise making more sense to grow slower).

I suggest that the time for 2x2 trees to grow is increased, though dark and pale oaks remain in question, as these are significantly smaller than other 2x2s.