Add "Fake User" setting for traits + reorder trait UI

[MoritzBrueckner]

Traits now have a Fake User setting. If set to true, the trait will be exported even if it is deactivated. This fixes #1529.

I've also slightly changed the trait UI:
Before:

After:

[Sandy10000]

Thank you for your support. I downloaded the file and checked it using the test file "Trait.blend".

Check the fake user checkbox of the trait "Bullet" set in the object "projectile".

Press the space bar to shoot one shot and hit the floor to disappear. No problems occur while repeating this.

Shooting the second shot before it disappears after shooting the first one will freeze without error. It seems that there are still some problems.

[MoritzBrueckner]

Oh ok I had this issue as well (only if two bullets are visible at the same time) but after changing the code to the current one (I had some different ideas before) I could not reproduce it anymore. The problem is probably at some other place, I will try to find the issue, thanks for testing :)

Edit: I tried it again (with a clean redownload of your test file from the above linked issue + stashed my other armory changes in Git so that they don't interfere) and I still cannot reproduce that problem anymore. It just works, I can spam the space key as much as I want and it doesn't freeze.
But as I said I had the same issue before so something is still weird, but possibly not related to this PR.