Clean up menus and unused menu items

main.js

@@ -1,5 +1,33 @@
 const { app, BrowserWindow, Menu, dialog, ipcMain, fs } = require('electron');
 
+function showAboutDialog(parentWindow) {
+    const detail = [
+	'TRIM.SP simulation GUI for low-energy ion implantation studies.',
+	`Version: ${app.getVersion()}`,
+	'License: GNU General Public License v2 (GPL-2.0).',
+	'Maintained by the Low Energy Muons group at the Paul Scherrer Institute.',
+	'Main contributor: Zaher Salman.',
+	'',
+	'Key references:',
+	'J. P. Biersack and W. Eckstein, Appl. Phys. A 34, 73-94 (1984).',
+	'W. Eckstein, Computer Simulation of Ion-Solid Interactions (1991).',
+	'E. Morenzoni et al., NIM B 192, 245-266 (2002).',
+	'',
+	'Project repositories:',
+	'Bitbucket: bitbucket.org/zaher-salman/trimsp',
+	'Gitea: gitea.psi.ch/LMU/TRIMSP'
+    ].join('\n');
+
+    dialog.showMessageBox(parentWindow, {
+	type: 'info',
+	title: 'About TrimSP',
+	message: 'TrimSP',
+	detail: detail,
+	buttons: ['OK'],
+	icon: parentWindow ? undefined : undefined
+    });
+}
+
 // Some Linux/remote desktop setups expose a broken GPU context to Electron.
 // Fall back to software rendering instead of crashing on startup.
 app.disableHardwareAcceleration();
@@ -214,18 +242,12 @@ function createWindow () {
 	{
 	    role: 'viewMenu'
 	},
-	{
-	    role: 'windowMenu'
-	},
 	{
 	    role: 'help',
 	    submenu: [
 		{
-		    role: 'about'
-		},
-		{
-		    label: 'Learn More',
-		    click () { require('electron').shell.openExternal('http://electron.atom.io') }
+		    label: 'About TrimSP',
+		    click () { showAboutDialog(win); }
 		}
 	    ]
 	}