4.16.13
Fixed techs showing '0 turns' and yet not being researched
Fixed trigger uniques with broken city filters
Only buildable improvements are viable comparisons for determining if a City Center can provide a resource
Added 'era number', 'speed modifier for stat' countables - by SomeTroglodyte
Add buildingFilter to building maintenance unique - By PLynx01
Add Civ unique dialogue when asking for Declaration of Friendship - By ReallyBasicName
Improved AI road planning - By metablaster