refactor and code cleanup and bugfix in UFO waypoint selection

refactored/unified waypoint selection into single function,
added some legibility here and there,
fixed critical flaw in landing zone waypoint selection.
if (!ground)
{
	if (ground)
	{
		throw Exception("Laws of space and time have become corrupted, Please run CHKDSK or SCANDISK on (C:) to repair these inconsistencies.");
	}
}