added safety checks for TSD sequence coordinates to avoid extracting beyond the edge of a chromosome.
added safety checks for TSD sequence coordinates to avoid extracting beyond the edge of a chromosome.

EichlerLab/pacbio_variant_caller,EichlerLab/pacbio_variant_caller,EichlerLab/pacbio_variant_caller,EichlerLab/pacbio_variant_caller,EichlerLab/pacbio_variant_caller