COMP: double is not the right sphinx keyword for indexing

see http://sphinx-doc.org/markup/misc.html#directive-index

.. index::

  pair: A; B

Change-Id: Idabf3fbec5e4983a7faff632b9ee1def485a2440
improve indexing in Normal Mesh example

Change-Id: I68aebc1bb595bedb9d00ac0884bf424a9df64b8d
make use of itk::MeshFileReader in normal mesh example

Change-Id: Ia4ae7513f4aa9c9fe0cab6e17f2db8f978eed36d
Improve indexing in Delaunay conforming example

Change-Id: Ie6b72f6fdb186b0e0e1a1a1e733492e5e7a0b361
improve indexing in Fast marching example

Change-Id: Ia13b3a5fcb00af8f6ce3270a971ae3f02f11435a
Merge changes Ia13b3a5f,Ie6b72f6f,Ia4ae7513,I68aebc1b,Idabf3fbe

* changes:
  improve indexing in Fast marching example
  Improve indexing in Delaunay conforming example
  make use of itk::MeshFileReader in normal mesh example
  improve indexing in Normal Mesh example
  COMP: double is not the right sphinx keyword for indexing