OO-2491: apply patch to always show coach comments (S. Clemenz), fix missing title of the course elements and their headers, fix missing legends, remove the old CSV and only use the OpenXML variant

OO-2484: add option "sendpartial", collect invalid addresses, convert addresses to identities and show an error in contact form

OO-2457: manual correction option will only update the score automatically and not the passed/failed status, clarify where own the user course env. and make it consistent for check list, don't show comment if there is only an empty string

OO-2479: reduce overhead everywhere, optimized and simplified query to count the participants of a group, bypass reloading the group set of identities, bypass reloading the base group of business group...

OO-2478: show a message if a user want to jump to a "softly" deleted course, don't send reminder of deleted course, show "deleted" course before "Members only"