Example fixes

Poking through the examples I noticed some of the p5.dom ones were broken.  I fixed them here.  Related to these examples, I have a question about the pixels array.  In p5, the pixels array is `width*height*4` i.e. `[r,g,b,a,r,g,b,a,r,g,b,a,r,g,b,a,etc.]`.  In Processing the pixels array, however, is `width*height` and each element of the array is the full 32bit color, i.e. `{rgba,rgba,rgba,etc}`.  Is there a reason for this change in p5?