KUbuntu 14.04 support restored (#1298)

* - [NEW] Add new interface and functionality to manage database file extension. (Implements feature request #659)

* - [FIX] Fixed CMake file to src.pro

* - Applied changes requested by mgrojo to uniform code with sqlitebrowser standards
- Add "history" when closing editor window, but reopen before closing preferences
- Revert some changes done by QtCreator

* Refuse from previous commit

* Additional changes requested by MKleusberg:
- [CHG] Always add "All files (*)" to filters
- [FIX] Removed unused include

* merged from master

* Merge sqlitebrowser master

* [FIX] Fixed compatibility to compile on KUbuntu 14.04 with Qt 5.2.1

* [FIX] Fix Qt version for QOpenGLWidget support on previous commit

* [CHG] Uniformed QT_VERSION_CHECK style
[CHG] Reverted macOS check on Mainwindow for OpenGL context creation

src/ExtendedTableWidget.cpp

@@ -18,6 +18,10 @@
 #include <QLineEdit>
 #include <limits>
 
+#if QT_VERSION < QT_VERSION_CHECK(5, 4, 0)
+    typedef QList<QByteArray> QByteArrayList;
+#endif
+
 QList<QByteArrayList> ExtendedTableWidget::m_buffer;
 QString ExtendedTableWidget::m_generatorStamp;