feat: update to WebGL 2

[dragoncoder047]

Is your feature request related to a problem? Please describe.

it's backwards compatible as far as I know so we shouldn't have to change much, the only hiccup is with shaders, since we don't have attribute and varying anymore, they're a combination of in and out, as well as needing the shader to start with "#version 300 es\n..."

Any more information?

WebGL 2 has vertex array objects support, it might improve performance

if we don't want to go around breaking everyone's shaders in v5000 we can still try VAOs by getting the extension OES_vertex_array_object

[dragoncoder047]

If we update to WebGL 2 then shaders also have access to the textureSize() function and we don't need to make the quads floating point 0-1 any more so the shader can do it all in pixel math.