Humann

* Update to sync with the latest MetaPhlAn database (v3.1).
- Detection of MetaPhlAn v3+ versions.
- ChocoPhlAn updated to include latest pangenomes.

* Update default to point to MetaCyc v24 pathways database.
* Reduce the length of the legend and fix two typos in humann_barplot script.
* Fix humann case and version in humann_databases script stdout.
* Update humann_barplot options in readme.

* ChocoPhlAn updated to include an additional 600 pangenomes.
* Updated to support the latest diamond version v0.+ (including default diamond install version plus databases).
* Utility mapping databases have been expanded to include additional EC mappings.
* Custom nucleotide database selection has been updated to only include pangenomes based on strict matching.
* Updates to the barplot script including support for matplotlib v3.

* Update pathways from v19 to Metacyc v24.
* Allow for shell in benchmark subprocess to allow for more commands.
* Use string instead of set to reduce memory usage by blastx_coverage.

* Add option for user to provide database location (merged from v2.8 branch).

* Change bowtie2 version check from error to warning to allow for conda bowtie2 package without version information.