Changes to IntervalList to ensure that only intervals defined against valid sequences can be loaded from file.
Changes to IntervalList to ensure that only intervals defined against valid sequences can be loaded from file.

annkupi/picard,broadinstitute/picard,broadinstitute/picard,alecw/picard,alecw/picard,broadinstitute/picard,annkupi/picard,broadinstitute/picard,annkupi/picard,alecw/picard,broadinstitute/picard,alecw/picard,nh13/picard,annkupi/picard,nh13/picard,nh13/picard,nh13/picard