Put functions from configuration.c into header

[PolynomialDivision]

Commit 1: Put add_ifcon to configuration.h

You want to use default_interface_conf as a basis to write an interface config. To do so, you write an empty interface config and use merge_ifconf to merge the default settings into your interface config. This commit puts merge_ifconf into the header.

Commit 2:

Put add_ifcon to configuration.h

If you want to add an interface with a different config you need to call
add_interface with an interface_conf as an argument. add_interface is
already located in the configuration.h. However, add_ifconf is not
available. The commit puts add_ifcon into the header. Further, it also
adds interface_confs to the header. The add_ifconf requires as a
parameter the interface_confs list.

[jech]

Why is this closed? It's no longer requested?

[PolynomialDivision]

Why is this closed? It's no longer requested?

Yes. I don't need it anymore. As you suggested I will go for filter to change the metric. :)