[suggestion] bughuntMaxEnemies percentage

[hth]

As additional parameter for calculating bughunt threshold, which will take into account the total number of enemies. Will be used only if produces a larger value than former.

Should be especially useful for large-scale base defences with complicated layout (eg. xPiratez sewers, where one can for eternity hunts just THREE remaining enemy units after slaying of three hundred). By default set as "0" so will not break anything.

PS Dunno should it apply to absolute totals or only to initialy spawned.