Broken Installation on Mojave (includes fix)

I know this is an old repo and things have moved on, but it would be amazing to upgrade this to work Mojave (and later Catalina).

On two machines running Mojave 10.14.7, I've had this fail to install with:

```
> ./src/scripts/check_reqs.js && xcodebuild

You need at least Xcode 7.0 when you are on OS X 10.11 El Capitan (you have version 11.1)
npm WARN reprocessing-example-cross-platform@1.0.3 No repository field.

npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! ios-deploy@1.9.2 preinstall: `./src/scripts/check_reqs.js && xcodebuild`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the ios-deploy@1.9.2 preinstall script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
```

To get past this, I had to update a few things:

* The reprocessing-scripts dependency to `"reprocessing-scripts": "Gregoirevda/reprocessing-scripts"`, which brings in the changes in this PR: https://github.com/jaredly/reprocessing-scripts/pull/5 -- would be awesome to merge this or something similar without the custom dependencies.

This then progresses further and eventually fails with complaints about bsb-native not being available.

* Updated the `bs-native` dependency in this project to 4.0.6, which allowed post install to complete 😸 . I've tried `4.0.7000`, which also works.

src/scripts/check_reqs.js と npm install に関係するパッケージ依存関係、特に reprocessing-scripts と bs-native から始めてください。報告されている macOS バージョンでインストールの失敗を再現し、その後、Xcode と bsb-native のエラーなしでインストールが完了することを確認してください。

索引モデルが issue の本文から書いたものです。