Allow leaflet to ignore DOM events for some nodes.

This change proposes a possible way to allow elements contained
inside the DOM structure of a leaflet map to mark themselves
in such a way that all events inside them are ignored by
leaflet and passed through to the other handlers in the system.

I believe this is needed for proper integration with frameworks
that connect to events at the document level.
Comment out debugging code.
Regen the dist files.
Handle case that comes up with SVG items/markers.
Rebuild library.
Merge pull request #1 from vrsource/dev/ignore_dom_events