ca'o'e VUhU experimental cmavo

mekso 4-nary operator: spherical harmonics on colatitudinal/polar angle a and azimuthal/longitudinal angle b of unassociated order c and associated order d.

Usually denoted Y^ml (\theta, \phi). The Condon-Shortley phase must be prepended to the definition. The normalization is chosen so that the integral over all (solid) angles of Y^ml(\Omega) conj(Y^n= \delta(m,n) \delta(l,k).