Moved the calculation of dw_frq out of spin and spectrometer loop.
This is done by having a special 1/0 spin numpy array, which turns on or off the values in the numpy array multiplication.
The multiplication needs to first axis expand dw, and then tile the arrays according to the numpy structure.
Task #7807 (https://gna.org/task/index.php?7807): Speed-up of dispersion models for Clustered analysis.
Authored by: tlinnet 2014-06-09
Parent: [r23757]
Child: [r23759]
