Voting (#3185)

* Basic voting

* Rewrite lobby in XAML.
Working lobby voting.

* Escape menu is now XAML.

* Vote menu works, custom votes, gamemode votes.

* Vote timeouts & administration.

Basically done now.

* I will now pretend I was never planning to code voting hotkeys.

* Make vote call UI a bit... funny.

* Fix exception on round restart.

* Fix some vote command definitions.

Content.Server/Voting/IVoteHandle.cs

@@ -0,0 +1,18 @@
+using Robust.Server.Player;
+
+namespace Content.Server.Voting
+{
+    public interface IVoteHandle
+    {
+        int Id { get; }
+        string Title { get; }
+        string InitiatorText { get; }
+        bool Finished { get; }
+        bool Cancelled { get; }
+
+        event VoteFinishedEventHandler OnFinished;
+        bool IsValidOption(int optionId);
+        void CastVote(IPlayerSession session, int? optionId);
+        void Cancel();
+    }
+}