Big Ships implementation

[noep]

Implement a structure for big ships and their parts.

A big ship should consist of multiple parts which can be individually destroyed, and the state of the individual parts should alter the behaviour of the entire vessels systems, such as shield, weapons or engines.

Due to Pawns (the only destructible entity) being dynamic entities, which one cannot attach to each other, restructuring of entity-classes is needed.

More information: BigShip and ​Forum

(The HeavyCruiser model can be used for an ingame implementation.)