rework VHints.TestLastEl: clear lastHovered if needed
rework VHints.TestLastEl: clear lastHovered if needed

changes:
* on timeout, clear lastHovered if needed
* also set a timer even under non-queue mode
* the timer callback does not call @reinit if no last rect
  * to ensure the client rect changes
* limit hintMarkers.length: < 64
  * 64 is just too large

gdh1995/vimium-plus,gdh1995/vimium-plus,gdh1995/vimium-plus