Applying ChannelScrolling to remove calculateDragAngle

To avoid angle calculation changed the logic to use virtual areas.
When try to drag or pan, check where the current touch point locates
and determine how to drag a page.

Change-Id: Id9bd08a69c4ac93ff385c8088e6c16bed5dc5f88
Signed-off-by: kiwon <kiwon98.lee@samsung.com>