bam2hints should verify alignments sorted by queryname

[nathanweeks]

When invoked without --exonhints or --nomult, bam2hints expects reads to be sorted by read name. However, in this case, it only checks that any sort order specified in the BAM header is != "unsorted":

https://github.com/Gaius-Augustus/Augustus/blob/e69fa139c7f3b1e55176c14a143b31df925b99bf/auxprogs/bam2hints/bam2hints.cc#L588

But this doesn't account for the common case where a BAM file is sorted by "coordinate".

It would be helpful if any SO tag were required to have the value "queryname"; i.e.:

  if(header.HasSortOrder() && header.SortOrder != "queryname" && IntOnly && Mult)