Apply dark theme on dialogs

Fixes #291

app/src/main/java/org/isoron/uhabits/activities/habits/edit/BaseDialog.java

@@ -39,6 +39,8 @@ import java.util.*;
 
 import butterknife.*;
 
+import static org.isoron.uhabits.activities.ThemeSwitcher.*;
+
 public abstract class BaseDialog extends AppCompatDialogFragment
 {
     @Nullable
@@ -65,7 +67,13 @@ public abstract class BaseDialog extends AppCompatDialogFragment
     @Override
     public int getTheme()
     {
-        return R.style.DialogWithTitle;
+        AppComponent component =
+            ((HabitsApplication) getContext().getApplicationContext()).getComponent();
+
+        if(component.getPreferences().getTheme() == THEME_LIGHT)
+            return R.style.DialogWithTitle;
+        else
+            return R.style.DarkDialogWithTitle;
     }
 
     @Override

app/src/main/res/values/styles.xml

@@ -260,4 +260,9 @@
     <style name="DialogWithTitle" parent="@style/Theme.AppCompat.Light.Dialog">
         <item name="windowNoTitle">false</item>
     </style>
+
+    <style name="DarkDialogWithTitle"
+           parent="@style/Theme.AppCompat.Dialog">
+        <item name="windowNoTitle">false</item>
+    </style>
 </resources>