Implemented bonus for multiple players repairing #3748

This works by finding the square root of the amount of players repairing, and multiplying the base HP restored by that. The square roots are cached to prevent extraneous calculations. I also changed a  `for(;;)` to `while(true)` to aid code quality. It's all compiled into `GOTO`s anyways
What is the logic here? Why do we only care about the first repairer? Why do we remove all of the repairers if only the first repairer doesn't satisfy the conditions?