Improve replay metadata and the replay browser

List of changes:

* Better and more filters with new layout, for both mods.

* Rename/Delete/Detele all functionality.

* Simplified ReplayMetadata class considerably by introducing a new
GameInformation data object. The new GameInformation class contains
more information than previously available so the new solution is not
compatible with old replays, meaning it can't read old replays.

* Better and cleaner game information gathering in order to be written
at the end of the replay file.

* Revert changes to ReplayConnection, no longer necessary.

* Better exception message on missing sprites and fonts.

* New "SpawnOccupant" class that holds all the information needed by the
MapPreviewWidget to visualize a spawn point. It was using Session.Client
before and it was necessary to separate it to be able to show information
not available at lobby time.

* Fix keyboard focus UI bug when closing a window would not remove focus.

OpenRA.Game/Network/ReplayRecorderConnection.cs

@@ -20,7 +20,6 @@ namespace OpenRA.Network
 	class ReplayRecorderConnection : IConnection
 	{
 		public ReplayMetadata Metadata;
-		public WinState LocalGameState = WinState.Undefined;
 
 		IConnection inner;
 		BinaryWriter writer;
@@ -107,7 +106,8 @@ namespace OpenRA.Network
 
 			if (Metadata != null)
 			{
-				Metadata.FinalizeReplayMetadata(DateTime.UtcNow, LocalGameState);
+				if (Metadata.GameInfo != null)
+					Metadata.GameInfo.EndTimeUtc = DateTime.UtcNow;
 				Metadata.Write(writer);
 			}