Fixing Chapter 12, and images

src/Python/Visualization/FlyingFrogSkinAndTissue.md

src/Python/Visualization/FlyingFrogSkinAndTissue.py

src/Python/Visualization/Frog.py

src/Python/Visualization/FrogBrain.py

src/Python/Visualization/FrogReconstruction.py

src/Python/Visualization/FrogSlice.py

src/Python/Visualization/ViewFrogA.py

src/Python/Visualization/ViewFrogSkinAndTissue.py

src/Testing/Baseline/Python/Visualization/TestFrogBrain.png

.../Baseline/Python/Visualization/TestFrogReconstruction.png

src/VTKBook/12Chapter12.md

src/VTKBookFigures.md

src/VTKBookLaTeX/VTKTextBook.md

src/VTKBookLaTeX/VTKTextBook.pdf