Localisation updates from http://translatewiki.net.
soap api: remove stray error_log

backport of commit d4316ba78dd48e1d0bad54b4a7f87f5860f2c6c6 from master
Remove test files added by mistake
Documentation: added Entity Relationship Diagram
Documentation: added ERD to developers manual
Documentation: revised ERD

Replace various INT fields with BOOLEAN
Revised ERD readme file

- updated Editing Recommendation
- Udate Documentation instructions