Handle different init() signatures in a generic and type safe way. An adapter is selected at compile-time based on the signature of the init function. The adapter is stored in the module struct. At run-time the adapter unpacks the users init function and provides the requested arguments.

Passing unused parameters isn't necessary any longer.

Cosmetics and corner case tests, like the void init function.

Replaced operator() with a plain static member function.

Renamed struct field 'init' to 'nm_init'.

The private argument is pretty useless since it is restricted to a compile-time constant. The only place to access this constant private value is the init function. This really makes no sense. Removing.

This reverts commit dff8b1b.

* do not attempt to inline registerAddon
* removed C++11 variant
* diff hygiene: respect line ownership in macros
* cosmetics

Not sure how, but apparently I lost some changes in the rebase yesterday. Also not sure how I didn't notice. Anyway, this should do it.