- 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 suggested by Robin Getz locale .txt files can now be duplicated and
changed in the conf/lang/ directory and conf/plugin_lang/$plugin/
directory for plugins.

This reverts commit 48714142.
Additionally there is a new fix for FS#2107 that doesn't introduce a lot
of checks but instead ensures that the configuration option can't be set
to negative values when the configuration manager is used.

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.

The redirect target URL is constructed with escaped ampersands since b6258081.
Thanks to Chris Tapp for pointing out.