0030507: Visualization - introduce AIS_ViewController

ViewerTest_EventManager now inherits AIS_ViewController.
Platform-dependent user input handling within ViewerTest has been revised
to process events in common way through AIS_ViewController.
The mouse navigation has been changed, so that left mouse clicked
without modifers now rotates View.
The rubber-band selection can be activated via Alt+LeftMouseButton.
Selection is now done on mouse unclick and keyboard short-cuts take effect on unclick.

Aspect_Window::SetTitle() - added new method configuring Window title.
Introduced new types Aspect_Touch, Aspect_VKey, Aspect_ScrollDelta
for processing window events in platform-independent way.

src/AIS/AIS_DragAction.hxx

@@ -0,0 +1,26 @@
+// Copyright (c) 2018-2019 OPEN CASCADE SAS
+//
+// This file is part of Open CASCADE Technology software library.
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License version 2.1 as published
+// by the Free Software Foundation, with special exception defined in the file
+// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
+// distribution for complete text of the license and disclaimer of any warranty.
+//
+// Alternatively, this file may be used under the terms of Open CASCADE
+// commercial license or contractual agreement.
+
+#ifndef _AIS_DragAction_HeaderFile
+#define _AIS_DragAction_HeaderFile
+
+//! Dragging action.
+enum AIS_DragAction
+{
+  AIS_DragAction_Start,  //!< (try) start dragging object
+  AIS_DragAction_Update, //!< perform dragging (update position)
+  AIS_DragAction_Stop,   //!< stop dragging (save position)
+  AIS_DragAction_Abort,  //!< abort dragging (restore initial position)
+};
+
+#endif // _AIS_DragAction_HeaderFile