Fix display of record created for spurious characters between games in PGN files.

[RogerMarsh]

The sequence '... 1. e4 1-0 ff\n\n[Event ...' where the '1-0' ends a valid game and the '[Event' starts a valid game creates records for the two games plus a record for the invalid game 'ff'.

A hack was added to avoid crashes when attempting to display the PGN headers for the invalid game 'ff'.

Scrolling the list of games does not happen when the scroll action would bring the 'ff' game onto the display. The 'ff' game should be displayed in the 'Error' list but is not. Scrolling for an index is fine because the 'ff' game has no PGN tags and the game is not displayed in the list for any index.

'ff' cases have been seen in real PGN files, but it is assumed other character sequences with the effect described here are possible.