Pan Gesture Smoothing - Added APIs to change smoothing mode and amount

Pan Gesture Smoothing - Added APIs to change smoothing mode and amount

  DALI_PAN_SMOOTHING_MODE - Currently only 0 for off and 1 for a simple smoothing technique
  DALI_PAN_SMOOTHING_AMOUNT - From 0.0f for no smoothing to 1.0f for full smoothing

[problem]      Predicted panning is a little jittery at times
[cause]        Any slight error in touch data could skew the calculations a little
[solution]     Added smoothing phase

Change-Id: Ifc573419a63904fdadbc169fbeefd9dcae27dc0b
Signed-off-by: Adeel Kazmi <adeel.kazmi@samsung.com>