MIC requires that mpi.h be included before stdio.h (issue #12)
Adding indentation to indexes

In file EMfields3D.h the indentation is changed in the indexes of some vectors to improve reading.

This commit is mainly used to test the merging of modifications from multiple developers in the master branch of the GitHub repository.
Merge branch 'issue12' of https://github.com/alecjohnson/iPic3D into alecjohnson-issue12