#14886 edited the lecture/preparation view to use new sort_question-views, saveOrder is not checking whether there is already a list

Removed test cases because they weren't of much use after
the refactoring.

This will result in events being fired at the right time.
Most importantly, this ensures event-specific caching
annotations to work correctly.

getSession throws an HTTP exception, which is not
good style. Additionally, as it calls
getSessionFromKeyword internally -- which has a caching
annotation -- this caching mechanism will not work
because it only works if the method is called
from another object. This is due to the way Spring
is using proxies to intercept the calls.

This change also removes the "lockSession" method from CouchDB.
Instead, the more general update method is used which also
has the required caching annotations.

Added few pp Attributes to SessionInfo. Requests for Public Pool Sessions now return SessionInfo instead of Session.

count to NewAnswerEvent websocket broadcast. Task #14471

Updated copyright year and adjusted header format to be consistent over
all files and with other ARSnova projects.

preperation questions. Task #14343