Change default renderer

What do folks think about changing the default renderer to Canvas?

I'm occasionally getting ["Rats! WebGL hit a snag"](https://support.google.com/chrome/answer/2905826?p=ib_webgl&rd=1) when browsing in Chrome 28 and more frequently seeing `PERFORMANCE WARNING: Some textures are unrenderable.`.

We could count how many examples work better with which renderer, but I just wanted to hear some opinions first.

These snags are accompanied uncaught assertion errors (will dig for more detail) and this in the console:
```
WebGLRenderingContext: GL ERROR :GL_INVALID_FRAMEBUFFER_OPERATION : glClear: framebuffer incomplete (clear)
WebGLRenderingContext: GL ERROR :GL_INVALID_FRAMEBUFFER_OPERATION : glDrawArrays: framebuffer incomplete (clear)
WebGL: CONTEXT_LOST_WEBGL: loseContext: context lost
```