Add a lot more QS tiles

Fix #53. Also fix Bluetooth connection leaks.

mobile/src/main/java/be/mygod/vpnhotspot/manage/BluetoothTethering.kt

@@ -0,0 +1,51 @@
+package be.mygod.vpnhotspot.manage
+
+import android.annotation.SuppressLint
+import android.bluetooth.BluetoothAdapter
+import android.bluetooth.BluetoothProfile
+import android.content.Context
+import be.mygod.vpnhotspot.widget.SmartSnackbar
+import timber.log.Timber
+
+class BluetoothTethering(context: Context) : BluetoothProfile.ServiceListener, AutoCloseable {
+    companion object {
+        /**
+         * PAN Profile
+         * From BluetoothProfile.java.
+         */
+        private const val PAN = 5
+        private val isTetheringOn by lazy @SuppressLint("PrivateApi") {
+            Class.forName("android.bluetooth.BluetoothPan").getDeclaredMethod("isTetheringOn")
+        }
+    }
+
+    private val adapter = BluetoothAdapter.getDefaultAdapter()
+    private var pan: BluetoothProfile? = null
+    /**
+     * Based on: https://android.googlesource.com/platform/packages/apps/Settings/+/78d5efd/src/com/android/settings/TetherSettings.java
+     */
+    val active: Boolean get() {
+        val pan = pan
+        return adapter?.state == BluetoothAdapter.STATE_ON && pan != null && isTetheringOn.invoke(pan) as Boolean
+    }
+
+    init {
+        try {
+            adapter?.getProfileProxy(context, this, PAN)
+        } catch (e: SecurityException) {
+            Timber.w(e)
+            SmartSnackbar.make(e).show()
+        }
+    }
+
+    override fun onServiceDisconnected(profile: Int) {
+        pan = null
+    }
+    override fun onServiceConnected(profile: Int, proxy: BluetoothProfile) {
+        pan = proxy
+    }
+    override fun close() {
+        adapter?.closeProfileProxy(PAN, pan)
+        pan = null
+    }
+}