Use dialog for external changes (#1309)

* Ignore external changes after "Continue"

* Reload or Overwrite options

* Add AskSaveDialog.vala

* Introduce "locked" document state

* Lock document during loading; unlock after if writable

* Stop some functions if locked

* Modify save and save as functions for locked

* Make some funcs private

* Modify check file status function for locked

* Rewrite ask save location for dialog and locked

* Compile dialog

* Minor improvements

* Start unlocked after loading

* Handle closing changed locked documents

* Update saved status when locked status changes

* Amend tab tooltip when locked

* Rework external changes with dialog

* Connect focus-in handler with focus-out handler

* Fix focus in and overwrite

* Inline AskExternalChanges dialog

* Do not throw dialog if there are no unsaved internal edits

* Remove unused class

* Move some code back to original position

* Update last_save_content after loading external changes

* Check for external changes even when internal changes

* Only save deleted file if there are unsaved changes

* Update src/Services/Document.vala

Fix typo

Co-authored-by: Ryan Kornheisl <[email protected]>

* Use copy paste to autoload changed text

* Flag as not loaded while replacing text

* No undo on autoload

* Lose unused infobar

---------

Co-authored-by: Ryan Kornheisl <[email protected]>

src/MainWindow.vala

@@ -896,7 +896,7 @@ namespace Scratch {
                 if (doc.is_file_temporary == true) {
                     action_save_as ();
                 } else {
-                    doc.save_with_hold.begin (true);
+                    doc.save_request ();
                 }
             }
         }