Update icons for stages, pods, and boosters

The icons for stages, pods and boosters do not match the theme of the
rest of the component icons and are larger in size. This change includes
and updated set of icons for these assembly components.

Co-Authored-By: Billy Olsen <Billy.olsen@gmail.com>

swing/src/net/sf/openrocket/gui/dialogs/AboutDialog.java

@@ -40,7 +40,7 @@ public class AboutDialog extends JDialog {
 			"Daniel Williams (pod support, maintainer)<br>" +
 			"Joe Pfeiffer (maintainer)<br>" +
 			"Billy Olsen (maintainer)<br>" +
-			"Neil Weinstock (tester, forum support)<br>" +
+			"Neil Weinstock (tester, icons, forum support)<br>" +
 			"H. Craig Miller (tester)<br><br>" +
 			"<b>Translations by:</b><br><br>" +
 			"Tripoli France (French)<br>" +