Use WebGL instead of just plain canvas drawing

As I discussed recently with @skorlir and @qiemem, WebGL would, in many ways, be a preferable technology to use for the NetLogo View, since WebGL would use the machine's GPU efficiently and be very fast, as well as also providing nicer ways of doing some of the odd graphical things that we need to do in the View (e.g. using follow to keep a particular turtle in the center of the View while still respecting the wrapping of the topology).

However, I am currently considering this issue to be of low priority. It definitely should not be included in the 1.0 release. Right now, I think that we should hold off on it, because (a) it is a major change, and (b) I feel that browsers have not been supporting WebGL well for long enough that we can reasonably expect 90+% of our users to be able to run this with correct behavior and without them having to manually enable WebGL. Let's give this one some more time before acting on it.

The issue proposes replacing the NetLogo View's plain canvas drawing with WebGL for GPU use and improved graphical behavior. No files, tests, or concrete implementation scope are named; first map the current View renderer, and consider the work complete only when the required behavior works correctly in supported browsers.