Add .gitignore so that project does not always have uncommited changes due to xcuserdata
add comment clarifying default value for flipY
make MaplyViewController respect rotateGesture property
Make MaplyRemoteTileSource query tileInfo for validTile::, take zoom level into account in validTile::

also expose validTile:: in header
Double tap to zoom in, MaplyStyle, does not yet recenter map
add two finger tap to zoom out gesture, refactor all three zoom gestures to inherit from MaplyZoomGestureDelegate
don't check minZoom in valid tile, Steve says a tile bellow min zoom is still valid.
setup proper dependencies between pinch and 2 finger tap gesture recognizers
Turned the short circuit importance back on.
Merge branch 'develop' of https://github.com/trailbehind/WhirlyGlobe into trailbehind-develop
Minor pinch fix.  Turned on new zom gestures for 2D test view.
Added animations to the new Maply zooms.  Fixed the retina tracking problem for the Maply pan.