Spaces, not tabs.

Actually, I liked tabs much more. But it seems a lot
of IDEs and general reader do not handle them correctly,
or do not let you configure "1 tab == 4 spaces", so the code
was not always readable.

"git diff -w" for this commit is en empty list.

Signed-off-by: Luca Fulchir <luker@fenrirproject.org>