4.2.0 release

[iteman]

• [x] Create 4.2 branch for the release if it does not exist
• [x] Change the branch of the build status in README.md if the branch is newly created (4.2)
• [x] Change README.md on the release branch. (4.2)
• [x] Tag to the release on git with the command git tag -s v4.2.0 HEAD (4.2)
• [x] Push changes to GitHub with the command git push upstream 4.2 and git push upstream --tags (4.2)
• [x] Create a new draft release as Stagehand_TestRunner 4.2.0 (stable) (GitHub)
• [x] Write the description of the release
  • The release date in UTC TZ=UTC date
• [x] Publish the release
• [x] Update wiki pages (Home)
• [x] Update the version in README.md and composer.json from 4.2 to 4.3 if 4.2 branch is newly created (master)
• [x] Push changes to GitHub with the command git push upstream master (master)
• [x] Remove unnecessary releases in Packagist
• [x] Remove unnecessary branches in GitHub
• [x] Tweet the release