Two new examples for loadPixels

[AdilRabbani]

Added two new examples for loadPixels(). One generates a simple texture using pixels and the other averages image pixels.

[limzykenneth]

In #1954 the loadPixels() function that needed example is for the version of loadPixels() for the WebGL renderer (currently not showing up in the reference because it is marked as a private function, probably still work in progress). I feel we don't need extra example in this instance of loadPixes() as it doesn't demonstrate additional functionality of the method that isn't already covered by the original example.

P.S. There seems to be a lot of noise in in the commits that are just adding and removing whitespace.

[AdilRabbani]

Yes, Although there were no technical errors in the examples I wrote, the commit after going through the Travis CI, was not passing a few tests just because of some minor whitespaces. That's the reason I had to commit it, a few times, passing the test cases...

[limzykenneth]

You can run grunt test locally to run the same tests that are ran on Travis and you can also run npm run lint:fix to try to automatically fix any code style issues.

[Spongman]

I think that actually the #1954 issue is in error. The renderer methods are not exposed as part of the API, and shouldn't appear in the reference docs.

The correct list of methods missing examples can be found by running grunt yui doc:prod.

[limzykenneth]

Yeah, I'm thinking maybe they are outdated since we've only added the @private tag recently