move stuff around in subdirectories

cube_twisted_inset.mtl

cuboid.obj

cuboid_16998.mtl

layouts/3x5box_layout.obj

layouts/box_animal_fine_layout.obj

layouts/box_animal_layout.obj

layouts/cube_layout.obj

layouts/cube_twisted_inset.obj

layouts/cuboid_twisted_inset.obj

layouts/cylinder_layout_prism.obj

layouts/horse_layout.obj

layouts/horse_layout_challenge.obj

layouts/spot_layout.obj

spot_control_mesh.obj

target-meshes/3x5box.obj

target-meshes/3x5box_6416.obj

target-meshes/cow_6938.obj

target-meshes/cube_933.obj

target-meshes/cuboid_16998.obj

target-meshes/cylinder.obj