== MS_brow_chev_decomp


  Apply a decomposition of the elasticity tensor C, after: 
     Browaeys and Chevrot (GJI, v159, 667-678, 2004)

  Assumes that C is in its optimal orientation for decomposition

  [Ciso] = CIJ_brow_chev_decomp(C)
     Isotropic projection of the elastic tensor.

  [Ciso,Chex] = CIJ_brow_chev_decomp(C)
     Isotropic, and hexagonal parts of the elastic tensor

  [Ciso,Chex,Ctet,Cort,Cmon,Ctri] = CIJ_brow_chev_decomp(C)
     All parts of the elastic tensor
   
