basic api documentation
pinch/rotate bubbles, cancelable
also defaultActions are set to prevent scroll in any direction
Workaround for mouseup having `buttons: 0` on Firefox and IE

Fixes #62 tap doesn't work in Firefox
Make `buttons` follow DOM3 spec

Related #62 tap doesn't work in Firefox and IE11
Merge pull request #55 from forresto/patch-2

basic api documentation
Merge pull request #61 from sbmaxx/fixPinch

pinch/rotate bubbles, cancelable
Forward clientX and clientY to targetFinding.path

Fixes #60 Events are not dispatched properly
Keep better tally of "buttons" bitmask

Fixes #67 track stops working after right-mouse click
Merge pull request #71 from Polymer/button-mask

Keep better tally of "buttons" bitmask
Safari has a broken map.forEach, remove check in pointermap test