visualize tank geometry in tigl, apply fuselage methods for it

[sfreund-DLR]

Hi, with the new cpacs tank definition finalized, I'd like to request tigl support for it. The tank geometry is defined alike the fusealge geometry starting at the "hulls"-element. These would be the requested items

• visualize the tank in tigl viewer
• provide the tigl-fuselage alike methods for the tank

An examplary cpacs dataset is under development and will be added when finished.

This is an examplary view of an aircraft with tanks