1. Fix bug in sampling that was causing small region selections to not return stats (sent in an invalid range, the end pos, to vcfstatsalive).
2. Return stats from vcfstatsalive every 1000 records to increase responsiveness.
1. Fix code so that original data (instead of reduced point data) is used to obtain point data for selected region.  After points are filtered to correct region, then reduce data points to fit in ~900 px width.
2. Fix code that formatted # of variants sampled so that when total < 1000, the labels are centered appropriately.