memory_limit issues

1. The use of a shorthand notation in ini_set() is wrong. As per the PHP FAQ on using shorthand values: You may not use these shorthand notations outside of php.ini, instead use an integer value of bytes.

2. The configured memory_limit could already be higher than 16M (on PHP 5, the default value is 128M). Changing it to 16M without checking that before actually reduces the amount of memory available.

The attached patch fixes these issues.
--
Stefan Kudwien
_{unleashed mind}