Miniboone analyser fixes
Enable multichannel analysis for miniboone.
new parameter save_test_events=1 causes test events to be stored as weighted.eventsout.root
with normalization such that avg(weight)=total cross section
param.h: more informative input error messages
save_test_events=2 saves test events with nonzero weight to weighted.eventsout.root
empty isotope bug removed; mec will not happen on Hydrogen anymore
Some cleanups.