use snackbar when copying to clipboard

org.fox.ttrss/src/main/java/org/fox/ttrss/CommonActivity.java

@@ -224,8 +224,14 @@ public class CommonActivity extends ActionBarActivity implements SharedPreferenc
 			clipboard.setText(str);
 		}
 
-		Toast toast = Toast.makeText(this, R.string.text_copied_to_clipboard, Toast.LENGTH_SHORT);
-		toast.show();
+		Snackbar.make(findViewById(android.R.id.content), R.string.text_copied_to_clipboard, Snackbar.LENGTH_SHORT)
+				.setAction(R.string.dialog_close, new View.OnClickListener() {
+					@Override
+					public void onClick(View v) {
+
+					}
+				})
+				.show();
 	}
 
 	protected void setAppTheme(SharedPreferences prefs) {