Canvas renderer for large images

[BryonLewis]

Swaps the geoJS renderer from Webgl to Canvas when the image size exceeds 8192 (8k) in any dimension.
WebGL has a maximum texture size and this will allow larger images to be displayed in the renderer.

[waxlamp]

I think I found a bug... and I have one style suggestion. Let me know what you think.

[waxlamp]

Shouldn't this say webgl here?

If yes, then I'd also recommend creating a boolean value (bigImage or something like that) and using a ternary conditional expression right in the renderer entry definition. This would avoid defining a default and then mutating it on (slightly) complex logic -- I think that would make the code more legible.

[BryonLewis]

Thanks, by default it didn't have a renderer and would default to webGL. I added in the default value and forgot to remove it.

I've updated to your suggestion, the formatting is caused by the annoying line length limit.

[waxlamp]

The only other thing I notice now is that you don't need the params variable any longer--you can supply that object literal to geoViewer.value.createLayer() directly.