Drop the round launcher icon

It's better to focus on the adaptive icon for the future. See #830.

app/src/main/AndroidManifest.xml

@@ -19,7 +19,6 @@
         android:allowBackup="true"
         android:fullBackupContent="@xml/backupscheme"
         android:icon="@mipmap/ic_launcher"
-        android:roundIcon="@mipmap/ic_launcher_round"
         android:banner="@drawable/banner"
         android:label="@string/application_name"
         android:theme="@style/Theme.Termux"

art/ic_launcher_round.svg

@@ -1,21 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 48 48">
-
-    <!-- Screen and border. -->
-    <path fill="#000"
-          stroke="#BFCBCD"
-          stroke-width="2"
-          d="M 24, 24
-             m -21, 0
-             a 21,21 0 1,0 42,0
-             a 21,21 0 1,0 -42,0"
-    />
-
-    <!-- Block cursor. -->
-    <path fill="#FFF"
-          d="M15,15
-             l5,0
-             l0,10
-             l-5,0"
-    />
-
-</svg>