Button event signatures fixed for consistency

Button event signatures now "handlerMethod(eventSource, eventData)"
where eventData == { button }
changelog.txt update for button event signatures
Pinch zoom fix

The existing code failed on iPhone Safari iOS 6.x - event.detail was
always 0 causing only zoom out behavior.
changelog update for pinch zoom fix
changelog.txt update for Button event signatures
changelog.txt update for TileSource event sigs
Merge branch 'master' into Button-Event-Signatures
Post-merge quick fix
Check that zoom reference point is valid before using it
Add similar refPoint validity check to zoomBy
whitespace formatting change
Merge branch 'master' into Button-Event-Signatures
Merge branch 'master' into Pinch-Zoom-Fix

Conflicts:
	changelog.txt
Merge pull request #241 from msalsbery/Button-Event-Signatures

Button event signatures fixed for consistency (#224)
Merge pull request #247 from jmnetus/master

Check that zoom reference point is valid before using it
Changelog for #247
Merge pull request #244 from msalsbery/Pinch-Zoom-Fix

Pinch zoom fix
Changelog for #249