0.5.0-alpha1

• Complete rewrite of library
• Switched interface to return Promise
• Uses hidden iframe window to perform rendering, allowing async rendering and doesn't force the viewport to be scrolled to the top anymore.
• Better support for unicode
• Checkbox/radio button rendering
• SVG rendering
• iframe rendering
• Changed format for proxy requests, permitting binary responses with CORS headers as well
• Fixed many layering issues (see z-index tests)