Prepare for 0.22.0 release.

Prepare for 0.21.6 release

Merge pull request jazzband#462 from alex/0.12.5

Prepare for 0.12.5 release.

Prepare for 0.21.4 release.

Prepare for 0.21.3 release.

Merge pull request jazzband#436 from alex/0.21.1

Prepare for 0.21.1 release.

Merge pull request jazzband#434 from alex/0.21.0

Prepare for 0.21.0 release.

Merge pull request jazzband#419 from alex/0.20.0

Prepare for 0.20.0 release.

Merge pull request jazzband#412 from alex/0.19.1

Prepare for 0.19.1 release.

Merge pull request jazzband#411 from alex/0.19.0

Prepare for 0.19.0 release.