Support strict mode for system tethering

TODO: Set up rules when upstream interface not found.

mobile/src/main/java/be/mygod/vpnhotspot/App.kt

@@ -49,8 +49,9 @@ class App : Application() {
         val result = pref.getString(KEY_OPERATING_CHANNEL, null)?.toIntOrNull() ?: 0
         return if (result in 1..165) result else 0
     }
-    val masquerade: Boolean get() = pref.getBoolean("service.masquerade", true)
-    val dhcpWorkaround: Boolean get() = pref.getBoolean("service.dhcpWorkaround", false)
+    val masquerade get() = pref.getBoolean("service.masquerade", true)
+    val strict get() = app.pref.getBoolean("service.repeater.strict", false)
+    val dhcpWorkaround get() = pref.getBoolean("service.dhcpWorkaround", false)
 
     val cleanRoutings = Event0()
 }