Adding sorting options to `sumstatsvector`.

Updating `sumStatsVector.c` and `msStatsDQH.c` to allow more (no)
sorting options and updating the default sorting option.

The executable `sumstatsvector` will now accept 4 more sort index values
(8--11). These specify to group loci by taxon and to calculate moments
across the loci for each taxon, but without re-sorting the resulting
moments.

There is now an `allow_sorting` variable that gets set in
`sumStatsVector.c` according to the command line argument that sets the
sorting index variable `gSortPattern`. If the sort index is 0 or 8--11,
`allow_sorting` is set to 0, which causes all calls to `qsort` in
`msStatsDQH.c` to be skipped. Four is then subtracted from
`gSortPattern` if its value is 8--11, so that it will follow the same
grouping and moment-calculating behavior as the values 4--7, but with
any sorting turned off.

THE NEW DEFAULT SORT INDEX IS NOW 11! This behaves the same as the old
default 7 in terms of grouping by taxon, and taking means of summary
stats over loci, BUT it does NO SORTING over taxa.
Updating perl scripts that call `sumstatsvector`.

Updating all perl scripts that call `sumstatsvector` (dpp-msbayes.pl,
msbayes.pl, and obsSumStats.pl) to allow use of the new sorting index
options in `sumstatsvector` and to update the default value for this
option.

THE DEFAULT SORT INDEX FOR ALL THREE OF THESE PERL SCRIPTS IS NOW TO USE
SORT INDEX 11! This groups loci by taxon, takes the mean of the summary
statistics over loci for each taxon, and DOES NOT RESORT THE RESULTING
MEANS OVER TAXA. The old default did the same, but resorted the summary
stat means among the taxa by pi_between.