Release 0.53

* added ability to change the table prefix easy via config.json, please
read <http://yals.de/OQRv0Y> for more informations
* added setting cfgChangeURL2WB_URL, enable the rewriting of the
specified URL's  to the active WB_URL
* imageTweak now stores the optimized images in a subdirectory with the
WB_URL, this enable imageTweak to handle multiple domains at the same
time
* updated precheck.php to actual versions