Introduce end-of-line normalization

Make sure that no mixture of endline chars are present in develop and force auto-normalization in future commits.

Recipe:

$ echo "* text=auto" >.gitattributes
$ rm .git/index     # Remove the index to force Git to
$ git reset         # re-scan the working directory
$ git status        # Show files that will be normalized
$ git add -u
$ git add .gitattributes
$ git commit -m "Introduce end-of-line normalization"

See #391 (closed) .