Control bind that allows players to toggle shields

[IrateRedKite]

Fairly simple client addition: A control keybind that allows players to toggle their shields on and off as if they had jettisoned cargo. A few things to consider:

• If a player's shield is already down due to damage, it should not come back up if this bind is toggled off and then on again.
• Once toggled off, the shield should stay offline till the player toggles it back on.
• If possible, there should be some sort of state indicator here to avoid confusion when/if a player accidentally hits the keybind.
• This should probably not have a default binding and should require a player to go and set the key to do this.

[Lazrius]

This is also possible with the /shields command, but a client binding will have to wait until 4.2

[IrateRedKite]

/shields is not currently working, might be something to investigate as a fix? I'm a complete idiot, was a build behind. Updated to current core and this is now working as it should.