Fix bad indention

Ref to commit c9f8812 @vhuber.
@prudhomm I updated the vim magic modeline. The option `cino=N-s` should avoid
namespace indention for vim version > 7.2.
Depending on the distribution, users might have to enable modeline in their vimrc
`set ml`

For details, see also
[vim modeline](http://vim.wikia.com/wiki/Modeline_magic))
[cin](http://vimdoc.sourceforge.net/htmldoc/options.html#%27cindent%27)
[cin options values](http://vimdoc.sourceforge.net/htmldoc/indent.html#cinoptions-values)