convert changeRadioButton to fab

app/src/main/java/com/geeksville/mesh/ui/SettingsFragment.kt

@@ -831,10 +831,8 @@ class SettingsFragment : ScreenFragment("Settings"), Logging {
 
         if (curRadio != null) {
             binding.scanStatusText.text = getString(R.string.current_pair).format(curRadio)
-            binding.changeRadioButton.text = getString(R.string.change_radio)
         } else {
             binding.scanStatusText.text = getString(R.string.not_paired_yet)
-            binding.changeRadioButton.setText(R.string.select_radio)
         }
         binding.changeRadioButton.setOnClickListener {
             myActivity.startCompanionScan()

app/src/main/res/drawable/ic_twotone_add_24.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24"
+    android:tint="?attr/colorControlNormal">
+  <path
+      android:fillColor="@android:color/white"
+      android:pathData="M19,13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z"/>
+</vector>

app/src/main/res/layout/settings_fragment.xml

@@ -96,7 +96,7 @@
             android:layout_marginStart="16dp"
             android:layout_marginTop="16dp"
             app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintTop_toBottomOf="@+id/changeRadioButton">
+            app:layout_constraintTop_toBottomOf="@+id/scanStatusText">
 
             <RadioButton
                 android:id="@+id/radioButton2"
@@ -111,15 +111,15 @@
                 android:text="@string/test_devname2" />
         </RadioGroup>
 
-        <com.google.android.material.button.MaterialButton
+        <com.google.android.material.floatingactionbutton.FloatingActionButton
             android:id="@+id/changeRadioButton"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
-            android:layout_marginTop="16dp"
-            android:text="@string/select_radio"
+            android:layout_margin="16dp"
+            android:contentDescription="@string/change_radio"
+            app:srcCompat="@drawable/ic_twotone_add_24"
             app:layout_constraintEnd_toEndOf="parent"
-            app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintTop_toBottomOf="@+id/scanStatusText" />
+            app:layout_constraintBottom_toTopOf="@+id/reportBugButton" />
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/updateFirmwareButton"