'platform' package

--HG--
rename : src/spinehx/atlas/Texture.hx => src/spinehx/platform/nme/BitmapDataTexture.hx
rename : src/spinehx/renderers/SkeletonRenderer.hx => src/spinehx/platform/nme/renderers/SkeletonRenderer.hx
rename : src/spinehx/renderers/SkeletonRendererDebug.hx => src/spinehx/platform/nme/renderers/SkeletonRendererDebug.hx