Updated roadmap with specific maintenance release dates
[CSS] Optimised the CSS for the calendar of events plugin.
Merge pull request #5107 from pjackson28/updateroadmap

Updated roadmap with specific maintenance release dates
Merge pull request #5102 from thomasgohard/css-clean-up-cal-events

[CSS] Optimised the CSS for the calendar of events plugin
Calendar Events: Remove extra "&" from cleanup

Related to gh-5102
Fixed the submodule update script for the new branch
Fixed broken links in v3.1 info boxes