Tweak quickswitch thresholds

- Reduce slop for gestural mode (and apply multiplier to slop
  at checktime)
- When quickswitch threshold is passed, reduce the total movement
  check and reduce the velocity needed to fling to the next page
  to accommodate short swipes
- Use touch slop to determine scrolling in paged view, and only
  use paging slop to determine flinging to the next page (when
  easy flings are disabled (which is the default))

Bug: 157165240
Test: Ensure the flings in normal overview/paged views don't change,
      check short flings from quickswitching
Change-Id: Idd04ce23f53c06759e84ac8ad73cf2cc6dff6975