load channelFile items into system channels vector

[taclane]

When a channelFile is used for conventional systems, these channels are successfully created and monitored, but are not added to the system channels vector. Downstream plugins or other API calls may want to access a list of conventional channels assigned to a system with sys->get_channels() whether or not a channelFile is in use.

This change does not affect the methods trunk-recorder uses to set up conventional systems with a channelFile, it only loads those channels into the internal vector after the .csv file has been read.

[robotastic]

Great addition... I feel like we could also probably simplify this section of code now, since conventional talkgroups will now be loaded into the channels vector. I will go check it out tonight:

trunk-recorder/trunk-recorder/main.cc

Lines 1023 to 1037 in 34484fe

	if (system->has_channel_file()) {
	std::vector<Talkgroup *> talkgroups = system->get_talkgroups();
	for (vector<Talkgroup *>::iterator tg_it = talkgroups.begin(); tg_it != talkgroups.end(); tg_it++) {
	Talkgroup *tg = *tg_it;
	bool channel_added = setup_convetional_channel(system, tg->freq, tg->number);
	if (!channel_added) {
	BOOST_LOG_TRIVIAL(error) << "[" << system->get_short_name() << "]\t Unable to find a source for this conventional channel! Channel not added: " << format_freq(tg->freq) << " Talkgroup: " << tg->number;
	// return false;
	} else {
	system_added = true;
	}
	}
	} else {