potx 5.x-1.2

Fixed several bugs and got the 5.x and 6.x parser in line:

- #205100 by phirdina: plural translations were missing in exported po files due to bugos database logic

Leveling differences between 6.x and 5.x versions: - backported some code style fixes from 6.1
   - backported relevant README changes from 6.x
   - removed hook_node_types() support, as it is a Drual 4.6 construct, not supported anymore
   - ported region name and default user role detection from 6.1
   - ported back hook_perm() error detection from 6.2
   - ported duplication marking for installer strings in runtime export from 6.1
   - better code when no file version was indentifiable, so the file name is included at least

Upgrade is highly recommended, especially for l10n_server (http://drupal.org/project/l10n_server) users, who translate Drupal 6.