add changes for 8.0.0

Merge pull request echocat#359 from echocat/develop

prepare release 7.3.0 (fix metadata)

Merge pull request echocat#343 from echocat/develop

backmerge for 7.2.0

Merge pull request echocat#328 from echocat/develop

backmerge for release 7.1.0

Merge pull request echocat#326 from echocat/develop

backmerge for release 7.0.0

Merge pull request echocat#290 from echocat/develop

backmerge for release 6.0.4

Merge pull request echocat#280 from echocat/develop

back merge for 6.0.3

Merge pull request echocat#271 from echocat/develop

backmerge for release 6.0.2

Merge pull request echocat#266 from echocat/develop

`backmerge for release 6.0.1

Merge pull request echocat#258 from echocat/develop

backmerge for release 6.0.0