Nodes:
Add savanna nodes (appear in non-mgv6 mapgens only):
Add 'dirt with dry grass'.
Add 'dry grass' (dry tall grass).
Textures were derived from the green grass textures.
Mapgen aliases:
desert_stone does not exist, use redsandstone.
desert_sand does not exist, use redsand.
sandstonebrick does not exist, use sandstone.
stair_sandstonebrick does not exist, use stair_sandstone.
Ores:
Generate bedrock in lava_source too.
Change desert_stone to redsandstone.
Biomes:
Change desert_stone to redsandstone.
Change desert_sand to redsand.
Decorations:
Make bonusbox chest appear on all mgv6 surface nodes.
Add bonusbox chest to non-mgv6 mapgens.
Replace redundant multiple grass decorations with an equivalent
single grass decoration, because only 1 length is used in MultiCraft.
Change desert_sand to redsand.
General format cleanup.
Bedrock was not generating because the cluster size was larger than the
difference between 'y_min' and 'y_max'.
Edit 'y_max' to enable.
Bedrock was cut through by seabed sand, deep ocean and cave air.
Make bedrock generate in stone, sand, water and air.
