use unique_ptr for automatic deallocation
do not crash for missing images
use CoreImage for decoding/encoding images on osx/ios
fix gyp project
also allow underscores in token names
bump cocoa
use more modern libpng version instead of the system-provided one and fix compile errors
Merge branch 'master' into platform-image

Conflicts:
	gyp/install.gypi
use -lpthread instead of -pthread
fix image y reversal
use test suite as submodule instead of using npm
use binary mesa on travis to speed up build times
remove dependency on node
call correct image compare script
Merge pull request #531 from mapbox/remove-node

Remove dependency on node.js
Merge branch 'master' into platform-image
declare explicit MACOSX_DEPLOYMENT_TARGET - refs #529
bump cocoa bindings
Merge pull request #527 from mapbox/platform-image

Use platform-specific routines for decoding/encoding images
Get mapbox-gl-styles via submodule (fixes #511)