Discard some motion during pan gesture

Discard some motion during pan gesture

When event spend so long time, a lot of events are queued.

Ecore cannot skip these event, so we make some heuristic
threshold of discard motion events on pan gesture.

We can setup this value by PanGestuerDetector's member vaule.
The name is "MaximumMotionEventAge".
the time scale is millisecond.

Default age is UINT_MAX ms (~= 49 days)
That mean, we will not discard every motion events.
(Ecore event callback also use uint32_t type in ms.)

Change-Id: Ib721e81d690327dcbc6c6c58383b33c7d5560922
Signed-off-by: Eunki, Hong <eunkiki.hong@samsung.com>