Fix for excessive reference file openings, updated htsdk version to 2.8
Fixed problem with excessive reference file openings. Used the same approach as with SamReader.
Also updated htsjdk version to 2.8 and JDK to 1.8.
Fixed problem with excessive reference file openings. Used the same approach as with SamReader.
Also updated htsjdk version to 2.8 and JDK to 1.8.