This implements a function based system. Instead of passing in the
error code as first argument, the error code itself is a error class.
It already contains the correct error type, so while adding a new
error no one has to think about the error type anymore. In case a
single error code has more than one error type, the error class has
properties for the non default error types. Those can be used as
fallback.

This prevents typos, makes the implementation easier and it is less
verbose when writing the code for a new error.

The implementation itself does not interfere with the old
implementation. So the old and the new system can co-exist and it is
possible to slowly migrate the old ones to the new system.

This updates all internal errors to the new error type. While doing
so it removes unused errors.

A few errors currently seem to have the wrong type. To identify them
later, comments were added next to the error type.

This ports the errors to the new error system.

Some error types are not properly set. This adds comments which
ones are probably falty and to what they should be set instead.