Rename config.php

With the increasing use of the "replace files" method of upgrading/updating it would save a lot of problems if config.php was renamed, for example, config.php.blank to prevent it being overwritten (something that I have just done that - embarrassed).

As a new installation requires the user to CHMOD that file before running the install then asking them to rename it would not be too difficult - in fact the install routine could probably do it automatically.