The delayed pi-round change can now be triggered via a simple api call.
After the api call a timed task will be started, which executes the
necessary steps for a round change. 

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

Note that this is currently untested. :o

Introduced a new CouchDB view method, and a new field to divide
'skill_questions' into preparation, lecture, and flashcard
variants. The former question type 'flashcard' will be removed
soon.

question. See commit 990eb9fe.

**/lecturerquestion/{questionId}/answer/.

API specification.
Changed StatisticsController to allow requests without a trailing slash
to be consistent with the other **/statistics paths.

/questionbylecturer/* => [/session/{sessionKey}]/lecturerquestion/*
/questionbyaudience/* => [/session/{sessionKey}]/audiencequestion/*