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Merge branch 'develop'
Add restore button for old versions.
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Update README.md
Update README.md

Add section for feedback feature.
Update README.md
Merge branch 'develop'
[maven-release-plugin] prepare release 3.0.0
Reset pom.xml.
[maven-release-plugin] prepare release 3.0.0
[maven-release-plugin] prepare for next development iteration