Custom and extendable devices

[nezuo]

Instead of the built-in devices we have now we could let the user create their own devices or extend the default ones we provide.

Potential API:

local device = Device.new("Keyboard")
	:addControl("Space", Enum.KeyCode.Space, ButtonControl.new())

inputState:addDevice(device)

Considerations:

1. More boilerplate, user has to specify what devices they want.
2. Is it even helpful for the user to add their own devices or extend the existing ones?
3. How should the user access device's controls now? device:get("control") or device.control?
4. Is our definition of a control good enough for it to be a public API?
5. We would also need to export classes like ButtonControl and Axis2dControl.

[nezuo]

I think I might want to change the definition of controls which would help with 5.

:addControl("Space", Enum.KeyCode.Space, ValueKind.Boolean, function(input)
    return input.UserInputState == Enum.UserInputState.Begin
end)

The control's value would be calculated with the function when the Enum.KeyCode.Space input changes.
If we specify the ValueKind of the control we can derive information like it's default value and actuation.

[nezuo]

3 can be solved easily by turning Device into DeviceBuilder that has a build method that just returns the dictionary that maps name to control.

local device = DeviceBuilder.new("Keyboard")
	:addControl("Space", Enum.KeyCode.Space, ValueKind.Boolean, function(input)
		return input.UserInputState == Enum.UserInputState.Begin
	end)
	:build()

print(device.Space)