Fix annoying bug where in order to use SamLocusIterator as an iterator one first had to call the .iterator() method on it to prime it.  Now auto-primes.
Fix annoying bug where in order to use SamLocusIterator as an iterator one first had to call the .iterator() method on it to prime it.  Now auto-primes.

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