mcv crate; cloak delay; AI

MCV crate set to 0. This will be at the very least until there is a way to delay good units from showing up early game.
Cloak delay raised to 90 since it re-cloaks fast. This is because currently the stealth tank starts countdown while still in "attack mode", after the last missile was fired. Should be changed again to 1-2 seconds after  https://github.com/OpenRA/OpenRA/issues/2898 is implemented.
Added hard AI.
orca balance

Orca has been shown in playtesting to be too good in large groups. Reducing HP to 90 so that bike rockets, e3 rockets can kill in 3 shots instead of 4.
Returning ammo to 5 again, because adding that extra rocket ended up making a much bigger difference than expected.
Merge pull request #2915 from psydev/patch-1

mcv crate; cloak delay; AI... minor changes