In LeastSquaresProblem.Evaluation removed the getValue() method.

- The residuals are the really the values of the objective function
  that is being minimized.
- Forcing the value to be a real vector and the residual computed
  through subtraction is an unnecessary constraint. For example
  Rotation.distance() will compute a better residual than
  subtracting the quaternion elements of two rotations.
- Method was not used by any optimizer.

JIRA: MATH-1102

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1571306 13f79535-47bb-0310-9956-ffa450edef68
Make AbstractEvaluation public

Allow custom implementations of LeastSquaresProblem to use the default
methods for computing the covariance, rms, etc.

JIRA: MATH-1102

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1571307 13f79535-47bb-0310-9956-ffa450edef68