Do not update group value property when the change action is triggered

[Artmann]

This is a breaking change as it will modify the behaviour of the component.

Do not update the group value when the change action is triggered as it violates "Data Down, Actions Up".

{{#radio-button
	value="blue"
	groupValue=color
	changed=(action (mut color))}}
	Blue
{{/radio-button}}

Fixes #16

[raycohen]

as mentioned in #16 (comment) I don't believe DDAU works well in this case because it allows the data layer to get out of sync with what the page is displaying.

[Artmann]

Is'nt that a generic feature of DDAU? If you don't mutate your state correctly, stuff is going to break.

[raycohen]

normally if you don't mutate your state, your UI will just show the existing state.

in this case, the user interaction will change the radio's state in the DOM. if you choose not to update your state (or forget), your state will think the value is off but the page is displaying it as on (or vice-versa)

imagine if you instead created a radio button component that did not use the input type=radio element, but rather just divs and images/css. then with DDAU if you don't mutate your state, the page will not change what the user sees.

[raycohen]

closing as this has gotten stale. please continue any discussion of DDAU in #16