Start implementing --script option
--script= loads script from file.
Working on script to drive python/field data demo
Templatize mesh iterators to work with old and new types
Fix unit test
Working on passing legacy mesh to ShowMesh
Include guard fix
Can visualize legacy meshes.

Next stop, fields with data!
Copy/Paste ShowMesh code to ShowField
Clang fix
Stubbed data on field via C++
Non-python latvol with stubbed data
ShowMesh pseudocode: node normals and values
Clang fix. Closes #295, closes #50, closes #309.