New configuration framework

[knifter]

Split configuration structs per operation unit:

struct way:
struct* settings = settings->getconfig(const char* identiefier, int instance_id)

or key/value way?:
int value = settings->getConfig("pidloop/%i/%s", instance_id, "setpoint")

Either way structs don't contain eachother and configuration is not invalidated each time a field is added