Added Clients/Editor.php

Added The clients editor page as well as extended changeContent() as
editContent() to allow args to be parsed. Extended History to support
args although still buggy. Added sql_query.php to handle all db queries
safely.
Added #extra to index.php to add support for extra info. No info being
parsed yet.
Dev Docs Added
Merge branch 'master' of https://github.com/JacquesLoubser/QReRP