Added helper tables step2tags and path2steps.
Added exception table which is a mirror of the bug table. Exceptions are automatically
recorded and can be viewd on admin screen when we choose to. Right now happening at only
one place: source of most of the errors which should be fixed now
Cleaned up the pathchoosing process. Common error from blank locations on steps should be
fixed now, otherwise we will get logging of the event into the exceptions table