- 'final' where possible
- do not assign to parameters
- removed duplicated code in GammaFunctions (which had a bug in it)
- warnings: do not save more than maxWanings warnings

Provide parameter values for each distribution separately +
honor semantics of common parameters like probability in [0,1] etc.

Few minor fixes of bugs discovered along the way.

Plus 'pgamma' external implemented.

+ necessary DPQ/RMath methods
+ move all XChisq to Chisq.java

called for the first time