Dali C#: Common Interface Define related changes

Dali C#: Common Interface Define related changes

- OnStage() : changed/added into property of 'IsStageOn{get;}', changed into internal.
- View class inherit : changed to inherit from Actor (previously, CustomActor).
- BackgroundImage, Background are moved to /internal/view.cs
  because these return Dali.Property class which needs to be hidden in Common-Interface.
- KeyboardFocusManager naming changed : FocusManager, only class name is changed. need to change signal's names also.
- KeyInputFocusManager : Instance property added.
- Stage : BackgroundColor, Size property return types are changed from Dali.Color, Dali.Size to Vector4, Vector2.
- Animation FinishedSignal : Event Handler has been changed to get only one argument. Event chaining enabled.
- Animation EndAction : naming is changed as 'Cancel' and 'Stop', Stop(action) argument changed. EndAction property added.
- Duration : set as Milli-second unit as default. (DurationMilliSecs: removed)
- AnimateTo : Animation API interface changed.
- Add user custom alphafunction : enable user defined simple custom alphafunction,
  add sample app "user-alphafunction.cs" how to define custom alphafunction and delegate
- hello-world.cs, user-alphafunction.cs have been changed.
- Dali build server error : break in dali-demo build, some rpm package get failed. remove dali csharp spec file.
- EventHandler pattern changed : .NET provided EventHandler used. Stage Wheel event is not working.
  (but EventProcessingFinished works when actual mouse wheel controled.) Stage's event property naming changed.

Change-Id: I0b5e1af8817c94f757ff7bf9e87bc850c4cbd50b
Signed-off-by: dongsug.song <dongsug.song@samsung.com>