Extract reordering logic from core as optional plugin

[wilsonpage]

IMO this is a non-core feature and doesn't need to bloat the core library. Happy to be proven wrong if people think otherwise :)

[wilsonpage]

@etiennesegonzac is re-ordering the same as 'edit-mode'?

[etiennesegonzac]

currently yes. but we might end up with
list -> list with edit (selection) mode -> list with reordering

[wilsonpage]

I'm still thinking selection could be handled purely on user side, but I might be overlooking things.

[etiennesegonzac]

It depends of how much internal access will be needed to do a nicely scheduled transition I guess, we'll see!

[wilsonpage]

You mean moving from selected -> unselected should go through scheduler?

[etiennesegonzac]

oh no :)
I mean the transition where all the checkboxes/reordering tips appears.
Might be a non-issue (because of the small dom) but current gaia apps struggle with this.

[wilsonpage]

I'm thinking:

1. User changes some state somewhere in their app
2. They call list.render()
3. This shedules a mutate task
4. This triggers their render method which draws a checkbox

[wilsonpage]

The above should ensure that the user never directly touches the DOM

[wilsonpage]

Their render method might look something like:

render: function(el, data, index) {
  el.classList.toggle('select-mode', appSelectModeFlag);
  ...
}

[etiennesegonzac]

Closing as a dupe of #17

[wilsonpage]

Fixed by 0948d0e