v2.4.1 playlist editor fixes release

Enhancements this release:

• simplified workflow for adding new airname #66
• reject playlist creation if duration < 15 minutes or > 6 hours
• swap artist name iff from ZK library and single word after comma, eg Band, The #58

Fixes/obsoletes:

• Playlist editor showing duplicate delete button #68
• Add airname not preselecting #61
• Airname not prefilled #67

Thanks to @eric-gilbertson for his contributions to this release.