[NUI] Layout scroller pages api6 (#1185)

[NUI] Layout scroller pages api6 (#1185)

* [NUI.Components] LayoutScroller flick added

Flick support
Configurable Flick animation
Ensuring uniform duration of flick animation by removing flick multipler

Change-Id: Ib654a38cb2070c29520069a75b5782d458ab4da6

* [NUI.Components] Horizontal Scroll supported

* [NUI.Components] LayoutScroller with horizontal Pages support

Other features added:

FlickDurationModifier renamed to FlickAnimationSpeed
Defaults changed so faster.

Uses View API for Add/Remove child instead of the new dedicated API.
ScrollStart and ScrollEnd signals added
Vertical and Horizontal axis enums to set Horizontal or Vertical scrolling

Fixes:
Tap gesture doesn't stop pages scrolling mid way.
Flick in Pages should not stack pages changes. Must wait until scroll ended to flick again.

Change-Id: I8dcabff1e956b747987865ceb4272ccb2ce55061

* [NUI.Components] LayoutScroller renamed to Scrollable

Change-Id: I42805c3b240997d1921db4b3c1008b120d264cbb

* [NUI.Components] Scrollable derives from NUI.Components.Control

Change-Id: Iec6f083fe4601ceff40f74bbe1ae8de4d8da6917

* [NUI.Components] Scrollable Pages MatchParent fix

Fixed bug in which the Scrollable would be the size of it's content
even when set to MatchParent

Change-Id: I2be91b1a6f975b4e8aa2a132dc63009a21ef4b62

* [NUI] Rename component

Rename component Scrollable -> Scroll

* [NUI.Components] rename Scroll to ScrollableBase

* [NUI.Components] change PanGesture direction when scrolling direction is changed

When scrolling direction is changed, pan gesture direction should be changed.
This change makes ScrollableBase support nested list cases.