Opening Lines DB: Commentary not saved at move zero

[CodeAndCaffeine]

Hi, keep up the good work, love to train with "find best move" and "sequential opening lines". Here's one issue which I've stumbled across.

Opening Lines DB (reproducible on R2.05):

When this DB type is on move zero (no moves done) and you type anything in the commentary field (below the chess board), this can be done, but this data is not saved and lost after closing the DB. Currently, only commentaries on explicit moves are saved.

Leaving comments at the very beginning (no moves done) would be very helpful esp. for giving training instructions with a certain DB that contains several different first moves, so you can't be sure which one is displayed first when training in random order.

[lukasmonk]

These trainings allow messages to be displayed after each movement. An initial help message is not envisaged, which should have a different treatment and I don't know how to implement it right now.