[mtouch] Build extensions and the container app in the same mtouch process.

Build extensions and the container app in the same mtouch process, by storing
all the mtouch arguments when called to build extensions in a text file, and
then reloading those arguments when called to build the main app.

This is required if we want to share code between extensions and the
container.

tools/mtouch/Application.cs

@@ -104,6 +104,7 @@ namespace Xamarin.Bundler {
 
 		public bool IsExtension;
 		public List<string> Extensions = new List<string> (); // A list of the extensions this app contains.
+		public List<Application> AppExtensions = new List<Application> ();
 
 		public bool FastDev;
 

tools/mtouch/mtouch.cs

@@ -1400,7 +1400,31 @@ namespace Xamarin.Bundler
 			if (action == Action.RunRegistrar) {
 				app.RunRegistrar ();
 			} else if (action == Action.Build) {
+				if (app.IsExtension && !app.IsWatchExtension) {
+					var sb = new StringBuilder ();
+					foreach (var arg in args)
+						sb.AppendLine (arg);
+					File.WriteAllText (Path.Combine (Path.GetDirectoryName (app.AppDirectory), "build-arguments.txt"), sb.ToString ());
+				} else {
+					foreach (var appex in app.Extensions) {
+						var f_path = Path.Combine (appex, "..", "build-arguments.txt");
+						if (!File.Exists (f_path))
+							continue;
+						Action app_action;
+						app.AppExtensions.Add (ParseArguments (File.ReadAllLines (f_path), out app_action));
+						if (app_action != Action.Build)
+							throw ErrorHelper.CreateError (99, "Internal error: Extension build action is '{0}' when it should be 'Build'. Please file a bug report with a test case (http://bugzilla.xamarin.com).", app_action);
+					}
+
+					foreach (var appex in app.AppExtensions) {
+						Log ("Building {0}...", appex.BundleId);
+						appex.Build ();
+					}
+
+					if (app.AppExtensions.Count > 0)
+						Log ("Building {0}...", app.BundleId);
 					app.Build ();
+				}
 			} else {
 				throw ErrorHelper.CreateError (99, "Internal error: Invalid action: {0}. Please file a bug report with a test case (http://bugzilla.xamarin.com).", action);
 			}