Setup $HOME/storage symlink for external symlink

At startup Termux now checks if there is external storage available,
and creates a private area on the external storage if one exists as
well as creating a symlink to the private are at $HOME/storage.

app/src/main/java/com/termux/app/TermuxActivity.java

@@ -293,6 +293,8 @@ public final class TermuxActivity extends Activity implements ServiceConnection
 
 		mTerminalView.checkForTypeface();
 		mTerminalView.checkForColors();
+
+		TermuxInstaller.setupStorageSymlink(this);
 	}
 
 	/**