openfl support

--HG--
rename : project.nmml => project.xml
rename : projectMixTest.nmml => projectMixTest.xml
rename : projectSkeletonTest.nmml => projectSkeletonTest.xml
js positioning fix
New demo urls
prepare for haxelib release

--HG--
rename : assets/goblins.atlas => samples/assets/goblins.atlas
rename : assets/goblins.json => samples/assets/goblins.json
rename : assets/goblins.png => samples/assets/goblins.png
rename : assets/goblins.skel => samples/assets/goblins.skel
rename : assets/nme.svg => samples/assets/nme.svg
rename : assets/spineboy.atlas => samples/assets/spineboy.atlas
rename : assets/spineboy.json => samples/assets/spineboy.json
rename : assets/spineboy.png => samples/assets/spineboy.png
rename : assets/spineboy.skel => samples/assets/spineboy.skel
rename : project.xml => samples/project.xml
rename : projectMixTest.xml => samples/projectMixTest.xml
rename : projectSkeletonTest.xml => samples/projectSkeletonTest.xml
rename : src-test/spinehx/AnimationStateTest.hx => samples/src/spinehx/AnimationStateTest.hx
rename : src-test/spinehx/MixTest.hx => samples/src/spinehx/MixTest.hx
rename : src-test/spinehx/SkeletonTest.hx => samples/src/spinehx/SkeletonTest.hx
haxelib release
Update README.md
Added support for setting up skins.
Handling default skins a little better.

Signed-off-by: Kipp Ashford <kipp@seven2.net>
Changed 'skin' to observable value.

Signed-off-by: Kipp Ashford <kipp@seven2.net>