Attention: $lang['register'] has been renamed to $lang['btn_register'],
anyone using that in any plugin or template should adjust it.

- better use of Latin terminology for DokuWiki
- ACL is not translated as AAA (Aditus Administrationis Aditus) but
  with ICA (Index Custodiae Aditus), which is a more literal translation
- minor corrections of grammar and logic
- The word "namespace" is more literally translated "spatium
  nominis", but according to other translations (like the Italian one),
  I preferred to use "genus".

As of VIM 7.3 it is no longer possible to specify the encoding in the
modeline. This gives an error message whenever such a file is opened,
thus this commit removes the enc setting from the modeline.

de / typo fix