Added coloured beds, new textures, fixed top

There are now 9 different coloured beds (roygbv, black, grey & white)
with new recipes (2 coloured wool + 1 white wool over 2 sticks), changed
textures and added 3D pillow. I've also changed the code to prevent the
top (pillow) node from destroying other nodes when the bed is placed.
Any previously placed old bed is replaced with a new, blue bed using the
alias function.