add: split CONCAVE edges type in two types

    add CONCAVE1 and CONCAVE2 as Edge3D type
    return the good type in generation
    change the 'if' with dict when appending typed edges
    add an array for the extra type and add thoses to data
add vis_2d_seg_seg and prettyfy visibility()
separate 2d and 3d intervals creation in init
add fct point_at in line3D

    maybe we should do something proper with all thoses
    nasty tuples of tuples or fcts than dict all w/ COORD, Beurk
    also add orientation attribute in LineAxis3D
Merge branch 'master' of github.com:perelo/Cubical3DPath

Conflicts:
	src/interval.py
add check of convex bending when computing ext point
remove this commit