combat bug fixed (thanks to an alert player!)

A Galactic Empire player (Seamus Donohue) noticed that combat seemed harder than it should be, especially when invading a more primitive planet.

Because the game is open-source, he dug into the MiniScript code, and quickly found the problem; a reversed operator in the gameRules script.  He proposed and tested a fix.  I double-checked the logic and the fix this morning, and he was absolutely right.  So I've updated the code on GitHub, and updated the builds here.

As a result, you'll now find it easier to conquer primitive planets than more advanced ones, as intended.  Thanks, Seamus!