Inconsistent .gitignore among cases

[MakisH]

In most cases, we don't have a .gitignore file, assuming that a developer would clean the result files (e.g. using Allclean) before commiting.

In other cases (e.g. tutorials/FSI/flap_perp/OpenFOAM-FEniCS/), we provide a .gitignore. In this specific case, the .gitignore is ignoring the complete case directories and then un-ignores specific files.

This inconsistency can lead in overseeing files when applying the same change in every tutorial.

A nice approach would be to have a global tutorials/.gitignore for the usual suspects (e.g. preCICE log files) and each tutorial could provide its own .gitignore for any special files.

[MakisH]

Suggestion (@fsimonis):

• Remove all the .gitignore files we have in case directories
• Create a global .gitignore to ignore common file formats (e.g. .log)
• In local .gitignore files exclude specific files.

[MakisH]

Update on the state: we currently have no global .gitignore file, but we do have a local .gitignore in some cases. Find files in the repository pressing t on the GitHub page of the repository.