Merge branch 'task/integrate-roadmap-extension' into 'develop'

Integrate typo3_roadmap extension

Closes #7, #10, #6, #13, #11, #14, #18, #19, #15, #21, #22, #23, #24, #25, #26, and #9

See merge request services/typo3.org/typo3.org!416
7 jobs for 579-select-categories-to-display-as-selector in 5 minutes and 52 seconds (queued for 3 seconds)