input spectra mode 2 issues

[dworogers]

The standard rz codes only allow mode 0 and mode 1 formats for .ensrc input spectra. However in the egs++ world, a mode 2 line spectrum is allowed (although I cannot find the documentation of it!). When a mode 2 spectrum is input to the rz codes, these is just a warning message that it isn't mode 0 or mode 1 but the code carries on. I suggest it should stop with an error message. In the g code it doesn't even provide the warning message and it gives very wrong answers, at least in the simulation I was doing. This also should stop when a mode 2 file is input. The ideal solution would be to make all codes handle the mode 2 line source spectra.