Nuclear Bombs now explode, tweak to reinforced wall ex_act()

This change is totally needed

• Nuclear bombs now explode into a 10, 20, 40 (and get deleted afterwards, for ultra nuke realism)
• This explosion is queued right after the explosion cutscene, which means living players get to look at it while the game processes the explosion itself
• The delay depends on how many secondary explosions are triggered (Read : Welding Tanks in range), but it shouldn't take forever to process

Reinforced Wall ex_act changes :

• ex_act 1 now changes all reinforced walls to space. Reducing all those reinforced walls to plating makes explosions look horrible. Ex_act 3 now has a MUCH lower probability of damaging the external cover to make repairs less skull-breaking for Engineers