How can I configure kproject to use a proxy ?

How can I configure kproject to use a proxy ?

Git is configured to use a proxy :
```
git config --global --add https.proxy http://user:password@url:port
git config --global --add http.proxy http://user:password@url:port
```

Gradle is configured to use a proxy :
```
systemProp.http.proxyHost=url
systemProp.https.proxyHost=url
systemProp.http.proxyUser=user
systemProp.https.proxyUser=user
systemProp.http.proxyPassword=password
systemProp.https.proxyPassword=password
systemProp.https.proxyPort=port
systemProp.http.proxyPort=port
```

IntelliJ IDEA is configured to use a proxy.

But when I try to use kproject, I have got this error :
```
An exception occurred applying plugin request [id: 'com.soywiz.kproject.settings', version: '0.0.4']
> Failed to apply plugin 'com.soywiz.kproject.settings'.
> https://github.com/korlibs/korge-ldtk.git: 407 Proxy Authentication Required
```

No files or tests are named. Start by reproducing the kproject invocation with the shown proxy settings and tracing the com.soywiz.kproject.settings plugin while it accesses https://github.com/korlibs/korge-ldtk.git. Done means the plugin can access the repository through an authenticated proxy.

Written by the indexing model from the issue text.