Support ignoring order of child elements in diffs

[stringbean]

We should be able to (optionally) treat this:

<parent>
    <child1/>
    <child2/>
</parent>

as being equal to:

<parent>
    <child2/>
    <child1/>
</parent>

[metyl]

Hi @stringbean maybe it should be another matcher called beSimiarXml or sth like this.
Any plans to implement this feature?

[stringbean]

It's definitely on my TODO list. My initial thought was that it would be part of the DiffOptions something like:

XmlCompare.compare(left, right, Set(DiffOption.IgnoreChildOrder))

Having a beSimilar shortcut would probably be a good idea though!