#43 fixed: Refactored Pointer intersection to assume child Views always exist within bounds of parent, greatly simplifying targeting code while still covering by far most use cases, as well as matching DFS used for rendering (i.e. such that Pointer target is sure to match what is rendered under the Pointer). Also Box2 contains elaborated to containsWorld (for use with getClientBoundingRect as the new standard to tie DOM bounds to View bounds) and containsLocal (as contains, previously).

Focus concept moved from Pointer to Phase.
Phase update cleaned up.
No more bubbling -- from now on sub-Views which wish to cause effects in their ancestors will call ancestor methods directly.
For now, Pointer selection on View-assigned DOM elements automatically sets Phase.focus (see Phase.update).
Non-root Views now have their Phase reference set.