-- Cleaned up code in updateDataForRead so that constant values where not computed in inner loops
-- BaseRecalibrator doesn't create it's own fasta index reader, it just piggy backs on the GATK one
-- ReadCovariates <init> now uses a thread local cache for it's int[][][] keys member variable. This stops us from recreating an expensive array over and over. In order to make this really work had to update recordValues in ContextCovariate so it writes 0s over base values its skipping because of low quality base clipping. Previously the values in the ReadCovariates keys were 0 because they were never modified by ContextCovariates. Now these values are actually zero'd out explicitly by the covariates.
Mauricio Carneiro
Mark DePristo