ConfigurableExtension(PreferenceScreen) support (#163)

* initial PreferenceScreen support, works with 'NeoXXX Scans' (pt-br)

* convert EditTextPreference to json successfully

* commit what I've got

* bring back the old SharedPreferences for CustomContext, implement Toast

* put back syer's implementation

AndroidCompat/src/main/java/androidx/preference/EditTextPreference.java

@@ -0,0 +1,46 @@
+package androidx.preference;
+
+import android.content.Context;
+
+public class EditTextPreference extends Preference {
+    private String title;
+    private CharSequence summary;
+    private CharSequence dialogTitle;
+    private CharSequence dialogMessage;
+
+    public EditTextPreference(Context context) {
+        super(context);
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public void setTitle(CharSequence title) {
+        this.title = (String) title;
+    }
+
+    public CharSequence getSummary() {
+        return summary;
+    }
+
+    public void setSummary(CharSequence summary) {
+        this.summary = summary;
+    }
+
+    public CharSequence getDialogTitle() {
+        return dialogTitle;
+    }
+
+    public void setDialogTitle(CharSequence dialogTitle) {
+        this.dialogTitle = dialogTitle;
+    }
+
+    public CharSequence getDialogMessage() {
+        return dialogMessage;
+    }
+
+    public void setDialogMessage(CharSequence dialogMessage) {
+        this.dialogMessage = dialogMessage;
+    }
+}