Enhancement - completion

- Implemented _projects and _tags reports to assist with tab
  completion scripts.

src/main.h

@@ -60,7 +60,9 @@ std::string handleExport ();
 std::string handleDone ();
 std::string handleModify ();
 std::string handleProjects ();
+std::string handleCompletionProjects ();
 std::string handleTags ();
+std::string handleCompletionTags ();
 std::string handleVersion ();
 std::string handleDelete ();
 std::string handleStart ();