Print help message

This will read from p_buffer to the stream.

Sets the offset to anywhere in the stream.

Moves the current offset forward, but never more than size.

This will write from the stream to p_buffer.

* @throws std::runtime_error in case of any invalid argument */

Printing the one and only help message I've stuck with a simple message format, nothing fancy.

---------------------------------------------------------------------------

---------------------------------------------------------------------------

Fetch threads based on the current FOV and level; prefetch will cache one level up and one level down of the current FOV (taking into account the down