add a checkbox for setting Sunday as the first day of the week

app/src/main/java/com/simplemobiletools/calendar/Config.java

@@ -29,4 +29,12 @@ public class Config {
     public void setIsDarkTheme(boolean isDarkTheme) {
         mPrefs.edit().putBoolean(Constants.IS_DARK_THEME, isDarkTheme).apply();
     }
+
+    public boolean getIsSundayFirst() {
+        return mPrefs.getBoolean(Constants.SUNDAY_FIRST, false);
+    }
+
+    public void setIsSundayFirst(boolean sundayFirst) {
+        mPrefs.edit().putBoolean(Constants.SUNDAY_FIRST, sundayFirst).apply();
+    }
 }

app/src/main/java/com/simplemobiletools/calendar/Constants.java

@@ -11,6 +11,7 @@ public class Constants {
     public static final String PREFS_KEY = "Calendar";
     public static final String IS_FIRST_RUN = "is_first_run";
     public static final String IS_DARK_THEME = "is_dark_theme";
+    public static final String SUNDAY_FIRST = "sunday_first";
     public static final String WIDGET_BG_COLOR = "widget_bg_color";
     public static final String WIDGET_TEXT_COLOR = "widget_text_color";
 }

app/src/main/java/com/simplemobiletools/calendar/activities/SettingsActivity.java

@@ -13,6 +13,7 @@ import butterknife.OnClick;
 
 public class SettingsActivity extends SimpleActivity {
     @BindView(R.id.settings_dark_theme) SwitchCompat mDarkThemeSwitch;
+    @BindView(R.id.settings_sunday_first) SwitchCompat mSundayFirstSwitch;
 
     private static Config mConfig;
 
@@ -24,12 +25,17 @@ public class SettingsActivity extends SimpleActivity {
         ButterKnife.bind(this);
 
         setupDarkTheme();
+        setupSundayFirst();
     }
 
     private void setupDarkTheme() {
         mDarkThemeSwitch.setChecked(mConfig.getIsDarkTheme());
     }
 
+    private void setupSundayFirst() {
+        mSundayFirstSwitch.setChecked(mConfig.getIsSundayFirst());
+    }
+
     @OnClick(R.id.settings_dark_theme_holder)
     public void handleDarkTheme() {
         mDarkThemeSwitch.setChecked(!mDarkThemeSwitch.isChecked());
@@ -37,6 +43,12 @@ public class SettingsActivity extends SimpleActivity {
         restartActivity();
     }
 
+    @OnClick(R.id.settings_sunday_first_holder)
+    public void handleSundayFirst() {
+        mSundayFirstSwitch.setChecked(!mSundayFirstSwitch.isChecked());
+        mConfig.setIsSundayFirst(mSundayFirstSwitch.isChecked());
+    }
+
     private void restartActivity() {
         TaskStackBuilder.create(getApplicationContext()).addNextIntentWithParentStack(getIntent()).startActivities();
     }

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

@@ -36,5 +36,31 @@
                 android:clickable="false"/>
 
         </RelativeLayout>
+
+        <RelativeLayout
+            android:id="@+id/settings_sunday_first_holder"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="@dimen/settings_padding"
+            android:background="?attr/selectableItemBackground"
+            android:padding="@dimen/activity_margin">
+
+            <TextView
+                android:id="@+id/settings_sunday_first_label"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_centerVertical="true"
+                android:paddingLeft="@dimen/settings_padding"
+                android:text="@string/sunday_first"/>
+
+            <android.support.v7.widget.SwitchCompat
+                android:id="@+id/settings_sunday_first"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_alignParentRight="true"
+                android:background="@null"
+                android:clickable="false"/>
+
+        </RelativeLayout>
     </LinearLayout>
 </ScrollView>

app/src/main/res/values-de/strings.xml

@@ -44,6 +44,7 @@
     <!-- Settings -->
     <string name="settings">Einstellungen</string>
     <string name="dark_theme">Dunkles Thema</string>
+    <string name="sunday_first">Sunday as first day</string>
 
     <!-- License -->
     <string name="notice">Diese App nutzt die folgenden Drittanbieterbibliotheken, die mein Leben einfacher machen. Danke.</string>

app/src/main/res/values-it/strings.xml

@@ -44,6 +44,7 @@
     <!-- Settings -->
     <string name="settings">Impostazioni</string>
     <string name="dark_theme">Tema scuro</string>
+    <string name="sunday_first">Sunday as first day</string>
 
     <!-- License -->
     <string name="notice">Questa app usa le seguenti librerie di terze parti per semplificarmi la vita. Grazie.</string>

app/src/main/res/values-ja/strings.xml

@@ -44,6 +44,7 @@
     <!-- Settings -->
     <string name="settings">設定</string>
     <string name="dark_theme">ダークテーマ</string>
+    <string name="sunday_first">Sunday as first day</string>
 
     <!-- License -->
     <string name="notice">このアプリは、私の人生を容易にするために、次のサードパーティのライブラリーを使用しています。 ありがとうございます。</string>

app/src/main/res/values-sv/strings.xml

@@ -44,6 +44,7 @@
     <!-- Settings -->
     <string name="settings">Inställningar</string>
     <string name="dark_theme">Mörkt tema</string>
+    <string name="sunday_first">Sunday as first day</string>
 
     <!-- License -->
     <string name="notice">Denna app använder följande tredjepartsbibliotek för att göra mitt liv enklare. Tack.</string>

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

@@ -45,6 +45,7 @@
     <!-- Settings -->
     <string name="settings">Settings</string>
     <string name="dark_theme">Dark theme</string>
+    <string name="sunday_first">Sunday as first day</string>
 
     <!-- License -->
     <string name="notice">This app uses the following third party libraries to make my life easier. Thank you.</string>