As I say the main sketch does nothing with my class yet as it doesn't compile, but here it is;
So, what I said in reply #1 is true. You are trying to hide the fact that dht.h is required from the sketch.
As I said, you can't do that.
Why, you might ask. Well, that's relatively simple. You don't own, maintain, or distribute the dht library. You just want to use it. But, suppose other people want to use your library. It won't compile or link for anyone that doesn't have the dht library installed. And, from looking at the sketch that uses (or will) your library, it isn't obvious that the dht library is needed.
One would actually have to look at the source for your library to see what other library or libraries are needed.
And that is the thing that the Arduino team does not want users to have to do.