UTR trimming sites are hard-coded

[dfornika]

We perform the trimUTRFromAlignment process to remove 5' and 3' untranslated regions from the aligned consensus. The positions where those trims are made are currently hard-coded on this line:

ncov2019-artic-nf/modules/illumina.nf

Line 307 in f1e4160

echo -e "\$(head -n 1 ${alignment} | cut -c 2-):266-29674" > non_utr.txt

Those positions should be made configurable via parameters (eg. --trim_utr_start and --trim_utr_end or similar). The default values should be set to the current values that we have hard-coded.