Referenceseeker

Changes
- Added option to select numbers of candidate reference genomes to assess
- Output N50/L50 statistics after scaffolding contigs
- Added Mash distance values to output

Bug fixes
- Fixed MeDuSa Python3 dependencies
- Added Java dependency to Dockerfile

This is a minor patch release fixing a MeDuSa related bug due to a missing MUMmer/show-coords binary.