otb and singularity containers.

prefetch_containers.sh is a script in scr it is automatically run by otb.sh, either NXF_SINGULARITY_CACHE has to be set, or it needs to be given a directory.

It will download the bare minimum of singularity containers needed to run otb. It has the following options:

• -p | --polish : the type of polish you'd like to use
• -b | --busco : do you plan on using busco?
• -l | --location : give prefetch a location to download, otherwise it will look for the nextflow singularity cache

There is also force_prefetch_containers.sh which is the same but with dangerous force flags and extra cache removal turned on.