mpwt 0.5.6

[ArnaudBelcour]

Add:

• a check for unfinished builds. If during a previous run a build failed, mpwt will delete it and relaunch it (issue Add a check to delete unfinished PathoLogic build. #49).
• a badge with a link to the preprint.

Fix:

• numerous issues in topf (issue Add gbk2pf converter. #30).
• numerous issues with taxon_id file when using circular, codon_table or element_type.
• numerous issues with raise error messages not showing.
• typos.