V4.2.0: Rewritten FE editor

Added

• Rewrite the FE editor for TYPO3 >= 10LTS
  (#1656, #1657, #1658, #1663, #1666, #1669, #1675, #1680, #1683, #1688, #1695)
• Add an Event model and repository
  (#1599, #1600, #1602, #1603, #1604, #1616, #1617, #1618, #1622, #1625, #1626, #1627, #1630, #1631, #1639, #1643)
• Add an Organizer model and repository (#1590, #1667)
• Add a Venue model and repository (#1586, #1667)
• Add an EventType model and repository (#1575, #1667)
• Add a Speaker model and repository (#1564, #1667)
• Add composer normalize to the CI toolchain (#1559)
• Add a services configuration file (#1548)

Changed

• Switch the coverage on CI from Xdebug to PCOV (#1614)
• Add feuserextrafields as a dependency (#1565)
• Switch to the TYPO3 coding standards package (#1553)
• Rename some Composer scripts (#1552)
• Require oelib >= 4.3.1 (#1525, #1650)
• Disable the legacy BE module in TYPO3 11LTS (#1521)

Deprecated

• Deprecate the legacy front-end editor (#1699)

Removed

• Drop the BE time-slot wizard (#1598)

Fixed

• Do not package the docker-compose configuration file (#1559)
• Get rid of unnecessary properties in the BE modules (#1554)
• 11LTS compatibility fixes (#1526, #1527, #1528)
• Fix type warnings for str_replace in the MailNotifier (#1524)