The other subfolders of tools/ had already been moved to either
editor/, misc/ or thirdparty/, so the hiding the editor code that
deep was no longer meaningful.
- `certs` and `editor_fonts` go to `thirdparty`
- `dist` and `scripts` go to a new `misc` folder
- `collada` and `doc` go to `tools/editor`
The next step will be to rename `tools/editor` to `editor` directly,
but this will be done at the right time to avoid breaking too many PRs.
