Nodal correction for L2 (not yet good enough).
Add lambda2 constituent.
Add M3 constituent.
Add constituents Mn with 3<=n<=12

To simplify things we neglect cos(N)**2 term in M4,MN4 and MS4 from here on.
Fix and add to tests for new constituents.
Add MKS2 and N4 constituents.
Add S4 and MSF.

NOTE: the nodal phase correction of MSF for now is taken to be the same as in FES2012, which I think is wrong (should be - of u_M2).