Cleaned up indention of initial php code
Use a template for fatal errors
Started working on a template for the main site
Cleaned up installer functions
Config has no closing tag any more
Continued working on main template
Changed base of twig's loader
Added macros for tags and messages
Preparing main file for template usage
Changed title of main template
Added all variables needed by the header (main page)
Fixed issues reported by phpcs
Made main page use a template
Added missing semicolon
Added new release of password-compat
Replaced old autoloader with composer's classmap autoloader
Added a mapping from backend's op parameter to class names

The mapping is restricted to classes actually used.  All plugins are
accessible through class PluginHandler.

The list might be to restrictive. It's based on current usage within
the codebase.
Slight refactoring

Now we don't ever have to test for an existing class when override
exists. We're only using the class when there's no override.