bugfix PGraph/edges impl for bezier & circle
add PInset, PFaceAccess & PNormalAccess protocols, bugfix Vec3/angle-between, rename normal3* into ortho-normal*, add point-towards fn
update ortho-normal refs, add PCenter, PFace/NormalAccess impls for gmesh, add PDistance impl for plane
update ortho-normal refs in meshio ns
add closest-line* fn, bugfix contains-point? & edges impls in line ns, add intersect-line for line3
update inset-polygon fn to only return seq of points, bugfix edges impl, add PInset impl for polygon
add inset-quad fn & PInset impl for quad3
add altitude & norm-altitude fns to triangle ns