Make methods of j.l.Math optimizable.

* Avoid to use native JS functions when possible: the optimizer
  does not know about these functions and cannot reason about
  their behavior.
* Add @inline to all simple methods.
* Make PI and E 'final val', because that's what they are as Java
  static final fields + it is better optimized.
Merge pull request #832 from sjrd/optimizable-jl-math-methods

Make methods of j.l.Math optimizable.