add an option in Unicycler to pass down --phred-offset 33 to SPAdes #279
Description
Sometimes SPAdes fails to autodetect the PHRED offset of Illumina reads:
0:00:00.002 1M / 3M INFO General (main.cpp : 86) Trying to determine PHRED offset
0:00:00.017 1M / 3M ERROR General (main.cpp : 89) Failed to determine offset! Specify it manually and restart, please!
(see e.g. ablab/spades#37)
To solve this problem, it would be great to add an option in Unicycler to pass down --phred-offset 33 to SPAdes.