- Users table model renamed to UsersTableModel- causes linker conflict

with class TableModel in accomodation plugin.
- Edit record dialog is now screen centered.
- Plugin tabs in application main window are now closable.

application/mainwindow.h

@@ -23,6 +23,8 @@ private slots:
 
     void on_actionOpen_database_triggered();
 
+    void on_tabWidget_tabCloseRequested(int index);
+
 private:
     Ui::MainWindow *ui;
 };