add a black splash screen

app/src/main/AndroidManifest.xml

@@ -12,8 +12,10 @@
         android:icon="@mipmap/launcher"
         android:label="@string/app_launcher_name"
         android:theme="@style/AppTheme">
+
         <activity
-            android:name=".activities.MainActivity">
+            android:name=".activities.SplashActivity"
+            android:theme="@style/SplashTheme">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN"/>
 
@@ -21,6 +23,8 @@
             </intent-filter>
         </activity>
 
+        <activity android:name=".activities.MainActivity"/>
+
         <activity
             android:name=".activities.WidgetMonthlyConfigureActivity"
             android:screenOrientation="portrait"

app/src/main/kotlin/com/simplemobiletools/calendar/activities/SplashActivity.kt

@@ -0,0 +1,13 @@
+package com.simplemobiletools.calendar.activities
+
+import android.content.Intent
+import android.os.Bundle
+import android.support.v7.app.AppCompatActivity
+
+class SplashActivity : AppCompatActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        startActivity(Intent(this, MainActivity::class.java))
+        finish()
+    }
+}