metal beds for wolf:et in md3 model format

two styles, one with a mattress and the other just the frame,
no shaders needed since they use the stock et shaders.

model locations:
models/mapobjects/furniture/metal_bed_mattress.md3
models/mapobjects/furniture/metal_bed_frame.md3

original mattress and pillow used from sd bunkbeds, new metal
bed/frame made in blender3d.

raybanb@gmail.com