Fix for PHP 7, more debugging output

Optimizations to autoloader

Autoloader should return true if it can handle the class so other registered autoloader don't execute.
require is faster than require_once and should be safe to use since the autoloader won't run if the class already exists

add convenience function for empty check without 0

This allows to quickly check if a variable is empty but keeps strings
and numbers evaluating to zero.

Fixed undefined error in html_denied()

Sorting by the sort number is too confusing since those are assigned
independently by different authors

Translation update (ru)

update Creative Commons licenses to 4.0. fixes #1286

https://wiki.creativecommons.org/wiki/License_versions
https://wiki.creativecommons.org/wiki/Frequently_Asked_Questions#Why_should_I_use_the_latest_version_of_the_Creative_Commons_licenses.3F

Translation update (sk)

Fix the flow of the navigation buttons in user manager

Fixed several undefined errors.

* Fixed identified issue with button spans by replacing missing closing span tag as identified by selfthinker, removed in ae614416.

* Changed the flow of the navigation button HTML so the navigation buttons actually flow to the right.

Translation update (bg)

Translation update (zh-tw)

Translation update (it)

Translation update (it)

Translation update (it)

Translation update (it)

Translation update (it)