delfin: variable number of expected deletion calls based on number of target regions
delfin: variable number of expected deletion calls based on number of target regions

previously this was fixed but resulted in vastly greater expected call
rate in small chromosomes compared to large.

ssadedin/groovy-ngs-utils,ssadedin/groovy-ngs-utils,ssadedin/groovy-ngs-utils,ssadedin/groovy-ngs-utils