Anti-Aliasing

[RafeHall]

Add support for some kind of anti-aliasing to meshes.

Some methods would be:

• MSAA which would bring about the problem of wgpu only supported 4xMSAA or none.
• SSAA expensive but would work irrelevant of backend but requires a whole new render pass to achieve.
• FXAA same as SSAA in that it would require a new render pass however is much more lightweight but can produce less than stellar results at times.
• Custom shader for meshes that smooths the edges, this could be done in the fragment shader not requiring an additional pass but will need a new pipeline if it gets used at the same time as any non-anti-aliased things.