Support for sorting on the OutputFiles tab.

[kyuuzou]

Hey!

I needed support for sorting on the Output Files tab, so I went ahead and implemented it.

I was only now noticing the contributing guidelines, which state: "Talk to us before doing the work -- we love contributions, but we might already be working on the same thing, or we might have different opinions on how it should be implemented."

I'm too late to speak to you first, but maybe we can speak now?

In summary, this code does the following:

• Adds support for sorting by file size and role on non-mobile builds, on the Output Files tab.
• Adds support for sorting by compressed and uncompressed file size on mobile builds, on the Output Files tab.

I'll be happy to make any changes deemed necessary if you feel as though this contribution could be useful.

Below you can see some screenshots of this in action, within the Test Project you provided: