Added Glass and Obsidian Glass door (doors mod)

mods/doors/README.txt

mods/doors/init.lua

mods/doors/sounds/door_close.ogg

mods/doors/sounds/door_open.ogg

mods/doors/textures/door_brown.png

mods/doors/textures/door_glass.png

mods/doors/textures/door_glass_a.png

mods/doors/textures/door_glass_b.png

mods/doors/textures/door_glass_side.png

mods/doors/textures/door_grey.png

mods/doors/textures/door_obsidian_glass.png

mods/doors/textures/door_obsidian_glass_a.png

mods/doors/textures/door_obsidian_glass_b.png

mods/doors/textures/door_obsidian_glass_side.png

mods/doors/textures/door_steel.png

mods/doors/textures/door_steel_a.png

mods/doors/textures/door_steel_b.png

mods/doors/textures/door_trapdoor.png

mods/doors/textures/door_trapdoor_side.png

mods/doors/textures/door_wood.png