Moved config into $GLOBALS
Moved request_uri into $GLOBALS
Modified all files accordingly
Modified logout page for future improvements (not deleting the entire $_SESSION)
Fixed LICENSEs, moved LICENSE for PHP files in /lib/php subfolder instead of /lib
Moved database function in class "Database";
Corrected database-using webpages accordingly;
Moved config file from PHP to JSON with more config variables;
Corrected login page redirection on wrong username or password.