Comet parameter: clear_mz_range

Example:
clear_mz_range = 0.0 0.0     parameter is ignored
clear_mz_range = 112.5 121.5     ignore all peaks between 112.5 and 121.5 m/z for iTRAQ 8-plex
clear_mz_range = 125.5 131.5     ignore all peaks between 125.5 and 131.5 m/z for TMT