[cnc-classic]  re-wrote structures.yaml

Structures should now have same values C&C Gold now. 
Helipad is not perfect (unit does not spawn in the center)
There may be issues with how the ion cannon does damage differently to weapons factory vs. airfield (also an issue in regular CNC fork).
List of buildings has been organized from basic to advanced, and in-game build menu has been changed to be more logical.