update BAM PG header line merging to produce a single chain if there were single chains in the input
split bam merging code into merging by coordinate and query name
- add wrappers for BamMergeCoordinate and BamMergeQueryName
- add collating input based on BamMergeCoordinate and BamMergeQueryName
add support for multiple occurences of input key=value pairs in ArgInfo class
add test program for query name baed BAM merging