Removed JSON.js code from file, since this was only necessary for IE6/7;
added preliminary support for file upload requests; added
vxJS.xhr.setHeader(field, value) method

Change-Id: I17e385bf20578bad2d858ec6cc4ae43d0f11ce66
Minor updates to file upload request

Change-Id: I3cd45d61047beffccac3d1da937fa66603d8856b
Added MIT license information; cleaned up some obsolete XHR code; added
polyfill for window.requestAnimationFrame()

Change-Id: I66df9b9ac6d9bef82359cfb91291094a15d05f48
Use window.requestAnimationFrame() instead of window.setTimeout()

Change-Id: Iff102e95b4f8fb011b05ce8e685f54451767b74a
Changed to an fps scaling factor

Change-Id: I8d50b6cfffe31f348a6c0435b6e4143786fe2ada