Add display_messages() function to Logbook and call it on loading the game.

This fixes the problem of messages being displayed only after the logbook.hide() is called.
Translated using Weblate (Catalan)

Currently translated at 100.0% (834 of 834 strings)
Translated using Weblate (Malayalam)

Currently translated at 0.4% (4 of 834 strings)
Translated using Weblate (Bulgarian)

Currently translated at 48.3% (403 of 834 strings)
Translated using Weblate (Catalan)

Currently translated at 100.0% (22 of 22 strings)
Translated using Weblate (Catalan)

Currently translated at 100.0% (22 of 22 strings)
Translated using Weblate (Catalan)

Currently translated at 100.0% (22 of 22 strings)
Translated using Weblate (Catalan)

Currently translated at 5.2% (10 of 191 strings)
Fixes to work with newest FIFE
Translated using Weblate (Catalan)

Currently translated at 100.0% (834 of 834 strings)
Adjust pyflakes names to new binary name
Fix formatting
Refactor mainsquaretab to handle its updates itself
Fixes #2278
Refactor main startup method
* Extract atlas loading into thread (that doesn't save time yet)
* Extract a ton of new methods for better readability
Update copyright year to 2014
Add last missing update
Translated using Weblate (Catalan)

Currently translated at 100.0% (22 of 22 strings)
Translated using Weblate (Russian)

Currently translated at 89.4% (746 of 834 strings)
Translated using Weblate (Russian)

Currently translated at 89.5% (747 of 834 strings)