* Added the notification for the third-party civilizations
If a civilizations knows about some two civilizations, it will be notified when:
* They declare the war
* They make a peace
* They sign the declaration of peace
* One denounce the other
Additionally, when civ enters a new era, all civs that know about it get a notification
* Fixed the translation `.properties`
* Cleanup
* Fix: 2 notifications for each peace treaty
Russia and America...
America and Russia...
* Typo
* Code style changes
* Resolved conflicts
* Simple getCommonKnownCivs() tests
