cluster/cassis: Zero-based promoters
cluster/cassis: Zero-based promoters

Correctly calculate zero-based promoter sequences in the
get_promoters method. Due to confusing zero-based (Python) vs. one-based
(GenBank) sequence access, the start coordinates of promoter sequences
starting directly at the beginning of the SeqRecord were set to 1.
Turned back into 0!

L--U--P--U--S/skeleton,L--U--P--U--S/skeleton