WIP: BRAINSFit is built and run but is not optimal for versor and BSpline transforms

BFit is tested and works for:
- linear transforms (rigid/ScaleVersor/ScaleSkewVersor/Affine)
- metric types (MMI, MSE, NC, JointHist)
- having several levels (e.g. rigid,ScaleVersor,Affine)
- input initial transform
- auto initial transform
- input fixed and moving masks
- auto masks mode

However, This branch "should NOT be MERGED" because BRAINSFit is not
stable for versor transforms and BSpline yet.
BFit should be held on at the curret step till LBFGSOptimizer and
Versor optimizers are moved to ITKv4.