Add log and sqrt operations into the math node

I want to experiment with color scaling for the mandelbrot set, and determining color based on logarithm of iteration count would probably look good, so I want it. Sqrt might be worth trying too

Ideally you should be able to pick the base for the log, but SKSL probably doesn’t support arbitrary log bases (or if it does, arbitrary log is probably slow), so having just log base e (natural log) and log base 2 would be a lot better than nothing

I would add to the list:

  • frac
  • to radians
  • to degrees
  • modulo
  • absolute
  • sign
  • exponent
  • floor
  • ceil
  • pow