Add elements for I23

[pblowey]

I23 can go to lower energies (longer wavelengths) than the other MX beamlines, so measuring around lower energy absorption edges is possible. Consequently, I23 are interested in being able to fit lower energy edges in MCA spectra. Previously, these lower energy edges would get included in the fit by having these lower energy edges defined in the peaks section of the I23 config file at /dls_sw/i23/software/pymca/pymca_new.cfg and the normal list of MX edges would be appended by the pymca_fitter service.

In recent changes, this functionality was lost and instead, if peaks were defined in the config file, the fitter would only use those peaks and would not append more. Having peaks hard-coded into the config file has a weakness as the batch fitting function from the PyMCA module will not work if an edge that is higher than the photon energy is included. Therefore, instead of having the peaks in the config file, this change adds a list of I23 elements that will be appended to the config file, so long as the edges sufficiently lower than the beam energy.

This change will require the peaks in /dls_sw/i23/software/pymca/pymca_new.cfg to be removed to take effect.