Visualize multiple pairs of meshes and skeletons with view3d

[huangziwei]

import skeliner as sk

name = [720575940552301329, 720575940554769884, 720575940556472535, 720575940560499902, 720575940564337565,
        720575940554550834, 720575940555141886, 720575940558814886, 720575940562055087, 720575940569769761]
meshes = [sk.io.load_mesh(f"../../../flatone/output/{n}/mesh_warped.ctm") for n in name]
skels = [sk.io.load_swc(f"../../../flatone/output/{n}/skeleton_warped.swc") for n in name]

sk.view3d(skels, meshes, scale=(1, 1e-3))

With this change, flatone can also do whole directory 3d viewing with very little effort:

 # view all warped meshes and skeletons in the default `output/` directory 
flatone view3d --warped