Checkpoint immediately after starting/upgrading the repository

This should fix a longstanding issue where quitting the core before the first checkpoint (1-2 hours after first launch) causes the database to become corrupt.

src/main/java/org/qortal/controller/Controller.java

@@ -417,6 +417,7 @@ public class Controller extends Thread {
 		try {
 			RepositoryFactory repositoryFactory = new HSQLDBRepositoryFactory(getRepositoryUrl());
 			RepositoryManager.setRepositoryFactory(repositoryFactory);
+			RepositoryManager.setRequestedCheckpoint(Boolean.TRUE);
 
 			try (final Repository repository = RepositoryManager.getRepository()) {
 				RepositoryManager.archive(repository);