A pre-install/upgrade configuration check script that checks php version and checks for the presence of certain php extensions. Results are shown and there is an explanation of what the results mean. It should be less confusing for new users who may have trouble interpreting results from phpinfo().
No check is made for a suitable database because there doesn't seem to be a reliable method of doing that without connecting to a db.
I'm not sure of mysql/mysqli extensions are needed when using PDO or not but the script checks for them anyway.
English only because it seemed to be inappropriate to add the complexity needed for alternate language support in a pre-installation script. If other languages are wanted it would be simpler for someone to just translate the full script.