Update the current NGC catalog to a new updated one

The NGC catalog used in Stellarium currently has many mistakes.
I had the very kind permission from Wolfgang Steinicke to use his updated NGC and IC catalogs available from his web site: http://www.klima-luft.de/steinicke/ngcic/rev2000/Explan.htm
His catalog provide more accurate positions, merge doublons etc..
He also provide more information on the type of the nebula. This info could be used to use icons matching the type of nebula, and also to draw ellipses for galaxies.

The code change should be located in modules/NebulaMgr.hpp/cpp and modules/Nebula.hpp/cpp

Skills needed: C++, Basic astronomy knowledge
Difficulty: easy, an ideal task to get started coding on Stellarium!