Support for older Android versions

[dopsi]

When trying to install this app on Android 4.4.4, I get an package processing error (Un problème est survenu lors de l'analyse du package.). I downloaded the APK from your website directly (it does show greyed out in F-Droid).

I assume this is an API/SDK version problem. Could you build the app for Android 4.4 (api 19) ? Or is there any functionnality that requires API 21 ?

[pacien]

Hello, the app uses some features requiring an API level >=21.
Contributions to make it backward compatible are welcomed.

[pacien]

The underlying tinc daemon and its dependencies (libressl) successfully compile for Android down to API 14 (ICS) thanks to PR #32.

However, it is not possible to bypass the VPN using addDisallowedApplication on API <21.
Immediate consequence is that tinc connexions to other daemons will be routed in the VPN itself. Using protect is not possible as it would require heavy modifications in native space.
Using exclusive routes is not possible either as they must be defined before the VPN service starts on Android.

Ideas to work around this issue are welcome.