Removing singleton usage: moving all send and save logic out of the MyTracks class.

This is a non-trivial step: I decentralized dialog creation (since it made no sense to have a single place creating a lot of completely unrelated dialogs), made invisible activities just for sending/saving, and changed menu handling a bit, all to decentralize those functions from MyTracks.

There's still a TODO to handle GET_LOGIN more nicely instead of returning from the depths of auth management into the current activity.

MyTracks/src/com/google/android/apps/mytracks/AccountChooser.java

@@ -29,7 +29,7 @@ import android.util.Log;
  * @author Sandor Dornbush
  */
 public class AccountChooser {
- 
+
   /**
    * The last selected account.
    */
@@ -68,13 +68,13 @@ public class AccountChooser {
       handler.handleAccountSelected(accounts[0]);
       return;
     }
-    
+
     // TODO This should be read out of a preference.
     if (selectedAccount != null) {
       handler.handleAccountSelected(selectedAccount);
       return;
     }
-    
+
     // Let the user choose.
     Log.e(Constants.TAG, "Multiple matching accounts found.");
     final AlertDialog.Builder builder = new AlertDialog.Builder(activity);