Egg and hen problem solved :)
* Test database connection on save settings -> prevents from making website unusable if connection is wrong
* Test server_path -> same
There is no config.php anymore, just config.local.php, which can be edited manually and also from admin panel
Move more config to settings (mainly mail_* + some other)
Remove mail_admin, wasnt used anywhere
Add return type to some functions
Add Twig settings(key) function
Possibility to save setting to db