Fixed Vim modeline

Hi!

`encoding` is not allowed in a Vim modeline.

`encoding` (`enc`) http://vimdoc.sourceforge.net/htmldoc/options.html#'fileencoding'
> Sets the character encoding used inside Vim.
> It applies to text in the buffers, registers, Strings in expressions, text stored in the viminfo file, etc.

`fileencoding` (`fenc`) http://vimdoc.sourceforge.net/htmldoc/options.html#'encoding'
> Sets the character encoding for the file of this buffer.
> When 'fileencoding' is different from 'encoding', conversion will be done when writing the file.

What I did:
+ Replaced  `encoding` by `fileencoding`
+ Added modeline where there is no added
+ Used a shorter version that fits in 80 characters

Best regards