Fixing issues in the TouchExplorer.

1. The up event for a long press was not properly adjusted as the
   long pressing finger may not be on top of the accessibility
   focused item.

2. There was a scenario where two finger swipe leads to a crash.
   One finger moves, second finger goes down but no finger moves,
   the first finger goes up, and now the second finger moves. All
   this has to happen before we decided that user is touch exploring.
   Very hard to happen, this is why we could not easily repro the
   crash.

3. We use the two finger vector angle to determine whether the
   user is dragging or not. However, in some cases we were
   unnecessarily waiting too long before performing the check
   and as a result the notification shade on Manta was not
   expandable.

bug:11341530
bug:11189225

Change-Id: Ieea39783444a1c20581f8addfd518d1c11485099