more zombies to spawn at once.

made them spawnable

-fixed the reduced speed when legs are destroyed
-broken arm makes them enrage

-higher walls

-giants now attack every 2.5 seconds
-fixed arm damage reduction
-tweaked number of giants
-tweaked damage to buildings

- gore skin used

- member health setted and minore damage improvements

- better knee-capping.

- added localized damages to legs and arms.
- giants now do less damages when arms are broken
- aim for the joints, or break them down.

-number of giants tweaked.
-safe zone added