---started work generalizing to all species contained in the TRANSP
file. In order to do calculation of beta and beta prime correctly need
densities and temperatures of electrons, ion species, impurities and
beam ions. Main correction which needs to be made later is to normalize
all ion densities and temperatures to the the reference species.
---fixed silly error with vth. Included all ion species in the output.
Normalized all densities and temperatures to the reference species.
Wrote documentation to clarify collision frequency calculation.
Merge branch 'master' of github.com:ferdinandvwyk/transp_read