Added fractionOfTotalBandwidth to the output menu files

Added the fractionOfTotalBandwidth parameter to the menu files when they're saved.  This value is calculated from dividing the rate for each trigger by the total rate for the menu, so that when fitting the menu for that particular total rate you should get the same menu back out.
I've done a brief test and there are minor fluctuations after the fit.  Nothing drastic though.