Support WebGL2 context

[skybluecat]

Hi, I found that when using a WebGL2 context and partykals with texture, the shader doesn't compile because "texture" is a reserved word in WebGL2. Can you please fix that by renaming the variables texture?

[RonenNess]

Hi @skybluecat, thanks for the tip, haven't really delved into WebGL2 since THREE don't officially support it yet.
Just making sure we're on the same page, you're talking about this right:

https://github.com/RonenNess/partykals/blob/master/partykals/material/shaders/fragment.js#L25

Or something else I should notice?
Thanks!

[skybluecat]

Yes, and also vec4 texture on line 44.