Set t3o special extensions to stable version

See merge request t3o/typo3.org!116

Resolve "Adds robots.txt file"

Closes #134

See merge request t3o/typo3.org!111

Add static includes from database

Closes #80

See merge request t3o/typo3.org!103

# Conflicts:
#   html/typo3conf/ext/t3org_layout/Configuration/TypoScript/Default/constants.txt

Resolve "[TASK] Change typo3-ter/cs_seo to clickstorm/cs_seo"

Closes #139

See merge request t3o/typo3.org!112

Resolve "[TASK] Remove "|" from the Titletag"

Closes #141

See merge request t3o/typo3.org!115

Resolve "Provide save and view button for news"

Closes #125

See merge request t3o/typo3.org!101

Resolve "[TASK] Remove migrate2gridelements from composer.json"

Closes #140

See merge request t3o/typo3.org!114

Resolve "migrate multi_content 2 gridelements"

Closes #138

See merge request t3o/typo3.org!113

Activate opcache clearing in deployment

See merge request t3o/typo3.org!109

Resolve "Titletag Event Detailpage"

Closes #137

See merge request t3o/typo3.org!108

Resolve "[TASK] Titletag News Detail"

Closes #135

See merge request t3o/typo3.org!107

Resolve "Install cs-seo"

Closes #133

See merge request t3o/typo3.org!106

Resolve "Update TYPO3 8.7.9"

Closes #131

See merge request t3o/typo3.org!105

Resolve "Specify extension versions"

Closes #130

See merge request t3o/typo3.org!104

Resolve "BE Login at stage does not work"

Closes #127

See merge request t3o/typo3.org!102