fractional_errors: Select the correct error window for each read
fractional_errors: Select the correct error window for each read

Use the read start index as the base index for the error vector window.
Separate the global error vector reference from the per-read stream
that includes the offset into the proper read region.

NVlabs/firepony,NVlabs/firepony,broadinstitute/firepony,broadinstitute/firepony,broadinstitute/firepony,NVlabs/firepony,NVlabs/firepony,broadinstitute/firepony