Give guns a potential range bonus, buff coil gun range

Now guns can add to maximum firing range, not just ammunition. I did this mainly so that we can have realistic behavior for stuff like bows (where the force comes from the weapon rather than the ammunition).

Also buffed the range of coil guns, because I've heard they're underwhelming for the difficulty and expense (mostly it's the UPS requirement that hurts them, I think), and I personally agree.