Added support for copying statistics
Changes to stats classes:
- copy constructor
- static copy(-,-)
- instance copy()
Added copy() to UnivariateStatistic and StorelessUnivariateStatistic
interfaces.

JIRA: MATH-212
Reported and patched by Jason C. HandUber 

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/branches/MATH_2_0@720030 13f79535-47bb-0310-9956-ffa450edef68
31 files changed