cigar: Avoid off-by-one when computing error vectors
cigar: Avoid off-by-one when computing error vectors

Reads with leading insertions were causing off-by-one errors when
marking indels in the insertion vector. Do not poke bits into the
insertion error vector outside the read range.

Same potential bug seems to have been present for deletions. This patch
fixes that as well.

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