Modify textures, add map generator necessities

mods/default/init.lua

mods/default/mapgen.lua

mods/default/textures/default_chest_front.png

mods/default/textures/default_chest_lock.png

mods/default/textures/default_chest_side.png

mods/default/textures/default_chest_top.png

mods/default/textures/default_cobble.png

mods/default/textures/default_dirt.png

mods/default/textures/default_grass.png

mods/default/textures/default_grass_side.png

mods/default/textures/default_jungletree.png

mods/default/textures/default_jungletree_top.png

mods/default/textures/default_lava.png

mods/default/textures/default_leaves.png

mods/default/textures/default_mese.png

mods/default/textures/default_mossycobble.png

mods/default/textures/default_sand.png

mods/default/textures/default_sapling.png

mods/default/textures/default_sign_wall.png

mods/default/textures/default_stone.png