Expose GameTitle, WindowIconSet and SplashLogo to content (#5475)

* Expose GameTitle to public

Requirement for upstream ss14 pr

* Missing method implemented

* Add windowiconset and splashlogo (I think this is what pjb meant?)

I don't think its worth it to add the other stuff (modules, assemblyprefix, autocnnect, clientassemblies)

* Docs

Robust.UnitTesting/GameControllerDummy.cs

@@ -66,5 +66,20 @@ namespace Robust.UnitTesting
         public void OverrideMainLoop(IGameLoop gameLoop)
         {
         }
+
+        public string GameTitle()
+        {
+            return "RobustToolbox";
+        }
+
+        public string WindowIconSet()
+        {
+            return "";
+        }
+
+        public string SplashLogo()
+        {
+            return "";
+        }
     }
 }