test suite 
     - run test and compare with expected results, generate diff's
     
// TO DO list, in no particular order:
//
// - !! merge calc_specdens_T0() and calc_specdens()
// - serialization of IterInfo: stream it to/from file, instead of performing
//   an independent NRG run for the DMNRG. This should be faster, and
//   would solve the round-off problem of the MKL library.
// - tables of relations between Invars in recalc_? functions..
//   Goal: no Number, Sspin in high-level functions !!
// - functions for checking compatibility relations between Invars for different
//   types of irreducible representations
// - boost/io/ios_state for changing precision and width during output
// - remove all kludgy #define's
// - fix triplet coefficients for 2-channel case (!!!!)
// - All spectra in a single map<>, names starting with 'T0' or 'FT' or 'DM'.
// - [DMNRG] rho[] to MatrixElements
// - remove end() calls from for loop headers
// - make XYFUNC a class with interpolation and other things one might need in a 
//   tabulated representation of a function
// - doxygen documentation
// - store dg in (QSi)(r) subspaces, instead of sending around qsrmax
