Hotfix #15

Hi! Some fixes for out last update: - Fixed Emperors gifts history not displaying correctly; - Fixed rivers tiles not drawing correctly in constructor mode; - Fixed 'set position in the center of the screen' for dialogs and messages; - Fixed crashing when you use plateau tiles in constuctor mode; - Fixed "undo last action" for farms; - Fixed a glitch when a wrong cost was displayed when destroing buildings; * Improved economy issues history window; * "Scribes messages" button is now highlihted when a city has new messages; * Improved paths rendering on information layers. See you soon! Cheers.