More CSV import fixes

Pre-configured imports in Import Dive Log File for CSV files should also
be cleared when the field separator is changed by the user.

Promoted DiveLogImportDialog::unknownImports to slot as per Canabrava's
suggestion and Hohndel's request.

Signed-off-by: Rodrigo Severo <rodrigo@fabricadeideias.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Add-main-window-full-screen-feature

This patch enables main window full screen mode by menu toggle or pressing
F11.

[Dirk Hohndel: whitespace cleanup]

Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>