Welder & CudaPT

I added support for intrinsic functions to Welder, including sqrt, abs, trig functions, etc.  The language is now pretty much full-featured in terms of basic operations!

I decided to throw the recent Welder ship into the path tracer, just to see how things look.  Thankfully, everything seems to look good!

Unfortunately, there are 3 very visible fireflies in this image, and I don't know why.  This was rendered with MLT for 10 minutes, so there definitely should not still be fireflies.  I'm going to have to investigate later :/ Still, the ship looks nice.