Release 2.3.0.0202: version-tagged images, changelog

- Drone: an image-tags step writes .tags (latest, commit SHA, changelog
  version) for the master publish, so each release can be pulled and
  rolled back by version. The master publish step no longer hardcodes tags.
- Version 2.2.0.0201 -> 2.3.0.0202 in xteve.go and changelog-beta.md, with
  a changelog entry covering the improvements branch.
- README / README-DEV describe the version tag.

xteve.go

@@ -23,7 +23,7 @@ const Name = "xTeVe"
 
 // Version : Version, die Build Nummer wird in der main func geparst.
 // Can be overwritten at build time: -ldflags "-X main.Version=..."
-var Version = "2.2.0.0201"
+var Version = "2.3.0.0202"
 
 // DBVersion : Datanbank Version
 const DBVersion = "2.1.0"