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

Note that due to the way it is currently implemented,
we have to clear the whole cache once a set of
questions published or unpublished in bulk.

Changing the Session object the way it was done previously
interferes with the new caching mechanism. The objects are
now long-lived so any direct changes to it which are not
in the spirit of its use case have to be removed. In this
case, changing the creator information invalidated many
of the isCreator checks sprinkled through the code, as
the new creator's name would have been the string
"not visible to you."

A NotFoundException was mistakenly thrown when the Session was set to
null via Socket.IO. Additionally, the user count was sent before it
had been updated.

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

#14448

databaseDao. Task #14478

count to NewAnswerEvent websocket broadcast. Task #14471

Bug was introduced in 0d050f02.

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

preperation questions. Task #14343

#14099