New stuff and improvements for chemanalysis.
- new plot PlotModels.plot_ratecoeff- Allows for the comparison of rate coefficients as calculated by ProDiMo as a function of T.
- Improvements and fixes for plot_reac_form_des
- new properties chemrates (chemical rates) and chemratecoeffs (rate coefficient) in Data_ProDiMo
- moved spnToLatex to the utils module