v0.5.0b: moved shattered's icons to a mipmap folder, deleted some icons

The mipmap folder is more flexible, see android documentation

I'm removing mdpi, hdpi, and xxhdpi as their none-perfect scaling (DPIs scale at 1.5x/2.25x/3x/4.5x/6x) looks awful. apps and launchers that still want to use those dpis can scale for themselves at runtime. Yes this is counter to android spec but I'd much rather suggest to external programs that they really should be using the xhdpi or xxxhdpi icons if possible. I'll likely change this back if it ends up breaking something

core/src/main/AndroidManifest.xml

@@ -23,7 +23,7 @@
 		android:xlargeScreens="true"/>
 
 	<application
-		android:icon="@drawable/ic_launcher"
+		android:icon="@mipmap/ic_launcher"
 		android:label="@string/app_name"
 		android:theme="@android:style/Theme.Black.NoTitleBar.Fullscreen"
 		android:allowBackup="false">