Upped hisat2 version to 2.2.1
Created by: batatasfritas
Mostly adding a file from spack 0.19
- commented out a patch-related section, since this would have implied adding several other dependencies
- added some python version selection (depends_on) to make the recipe a bit more robust
Reasons for this:
- version 2.2.1 supports Python 3
- version 2.2.0 only supports Python 2 (which is incompatible with other tools the user is using that depend on python 3)
(Once this is merged we'll have to update the installation of hisat2 on the clusters, but we can discuss this elsewhere)