Improved GEM cls model, bkg at high lumi, efficiecny for electron, neg s...

Improved GEM digitization model, including: alow digitization for all simhits; reduced efficiency for electron registration; improved cluster size model;  background model for ME0 improved;  background rates for ge11 ge21 and me0 corespond to the lumi of 5x10^{34}cm^{-2}s^{-1}; negative strip number bug fixed.