more improvements to periodic table
better XRF line selection
better XRF Display layout, + showing edge energies
better error handling for errors in scripts
adding XAFS example for Z+/-5 tests and phase-corrected FTs
adding XAFS example for Z+/-5 tests and phase-corrected FTs
updated ZnSe plots
updated Feffit doc for Z-sensitivity test
tweaked example script