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.Mods.RA/Widgets/Logic/SpawnSelectorTooltipLogic.cs

@@ -38,10 +38,10 @@ namespace OpenRA.Mods.RA.Widgets.Logic
 
 			tooltipContainer.BeforeRender = () =>
 			{
-				var client = preview.SpawnClients().Values.FirstOrDefault(c => c.SpawnPoint == preview.TooltipSpawnIndex);
+				var occupant = preview.SpawnOccupants().Values.FirstOrDefault(c => c.SpawnPoint == preview.TooltipSpawnIndex);
 
 				var teamWidth = 0;
-				if (client == null)
+				if (occupant == null)
 				{
 					labelText = "Available spawn";
 					playerCountry = null;
@@ -50,9 +50,9 @@ namespace OpenRA.Mods.RA.Widgets.Logic
 				}
 				else
 				{
-					labelText = client.Name;
-					playerCountry = client.Country;
-					playerTeam = client.Team;
+					labelText = occupant.PlayerName;
+					playerCountry = occupant.Country;
+					playerTeam = occupant.Team;
 					widget.Bounds.Height = playerTeam > 0 ? doubleHeight : singleHeight;
 					teamWidth = teamFont.Measure(team.GetText()).X;
 				}