The impulse is fairly weak, but it has no cooldown (of course). As long
as you can reliably click on them, you can keep dragging them around.
This builds charge.

Portal now COSTS charge, rather than gaining it, so that you bully
people until you can build a portal.

Also allows subsequent connections, but it's broken. Don't tell the git
gods that this commit is a lie

Within radius 8, attracts heroes with gravity.

In multiplayer, if there is only one hero 1, it is ok, but with more
than one, one hero 1 cannot place walls.

There however were some bugs that came with this, so I'm switching to
master to explore this.