#163 Knife(or sword) for robots

[FarooghKZ]

I think it's a sort of ramming, just more advanced ramming.there is a sharp sword or knife in front of robot which can come out and go in. i'm not sure about how to implement this.maybe a shot:

knife_shot();

Quickly comes out, damages the target robot and again goes in.or maybe two function two enable or disable it:

knife_enable();
knife_disable();

When it is enabled, it can damage those robots which come in front of our robot, but our robot will be slower when knife is enabled.