Work in progress for adding clipPath support.
Merge branch '2.x' into clip-path

* 2.x:
  Added logging for error condition, added sample SVG and image.
Finished implementation of <clipPath> (hopefully).
Changed the coins demo to also demonstrate <clipPath>.
Added warning when <clipPath> is encountered, removed warning for empty/missing clipPathUnits attribute.
Merge branch '2.x' into clip-path

* 2.x:
  ADDED: Can load SVG files from NSData sources, with working URL relative links. ADDED: SVG-image tag can point to local or remote SVG files (based on an idea by trilogysci)
  FIXED: removed confusing and incorrect SVGImage define
  FIXED: bug in use of NSURL. Modified License file
Create the SVGUnitTypes header for the SVG_UNIT_TYPE enum, moved SVGClipPathElement into SVG-DOM.
Merge branch '2.x' into clip-path

* 2.x:
  Remove methods since they aren't part of the spec.
  Added attribution for ImageAspectRatio.svg.
  Add ImageAspectRatio sample to the demo app.
  Implemented preserveAspectRatio for images.
  Revert "Work in progress (currently nicely broken) for preserveAspectRatio on SVGImageElement."
  Changed to share code for parsing preserveAspectRatio.
  Work in progress (currently nicely broken) for preserveAspectRatio on SVGImageElement.
Almost complete implementation of clipping in renderInContext.
Merge branch '2.x' into clip-path

* 2.x:
  Change SVGTextElement to not render blocky text on retina displays on iOS.
Changed to support retina resolution when making a bitmap mask.
Merge pull request #192 from dgileadi/clip-path

Support for clip path