- Fixed some spam bugs on acid & inferno common infected. Previously, each of their attacks could trigger acid/ flame on the ground, & their own acid/ flame was included. so they rose from normal threats to high threats. Now they have 5 seconds of cooldown on each acid/ flame attack, so they won't spam acid/ flame anymore.

- Added a new mutated common infected: Inferno Common Infected.
- Fixed the stacked traits when surrounded.

- Reduced explosion radius of the "Suicide Common Infected" from 250 to 150.