DALi C# binding - EventHandler Support

Added EvenHandler support for AccessibilityManager, Image, Popup, Stage, Actor,
ItemView, PropertyNotification, StyleManager, Animation,  KeyboardFocusManager,
RenderTask, Tapgesture, Application, Longpressgesture, ResourceImage, TextEditor,
Builder, ObjectRegistry, Scrollable, TextField, Button, Pageturnview, Scrollbar,
Timer, Control, Pangesture, ScrollView, VideoView, GaussianBlurView, Pinchgesture
and Slider classes.

By this, we use the normal C# way of adding EventHandler as delegates to user apps
and also hide IntPtr getting exposed to Users/app developers.
For ex:
(1) _application.Init += new Dali.AUIApplicationInitEventHandler(Initialize);
(2) _scrollView.OnRelayoutEvent += new Dali.Actor.OnRelayoutEventHandler(OnScrollViewRelayout);

Also updated the doxygen comments for the EventHandlers which will be exposed to
users/app developers.

Used verbs for event names. For example,
Actor.Touched += ;
Stage.Touched += ;
Actor.WheelMoved += ;
Actor.KeyPressed += ;
All events are changes as mentioned above.

Change-Id: I335f32381a6637c81d9c2379f69fa4d6f3e3c4c2
Signed-off-by: Ravi Nanjundappa <nravi.n@samsung.com>