Move default interface/command selection back to the common part.

- it is needed by the min-report
- it is needed by the state verification code

TODO is to create real multi-interface system:
- array INTERFACES
- instantiate all state files per interface
- create a function load_interface accepting an interface name and
perform all current "global" code from auto-ng.function in there
- make front-end scripts iterate INTERFACES or whatever by themselves
and execute load_interface + their own code as appropriate for each
interface.
Fix function reconfigure: explicitly delete wpa config before regenerating it.

netctl's wpa_make_config_file has a (silly) check on wpa config
existence.