added popup menu entries for collapse operations

 - closes #1
 - thanks to @Davincible for the suggestion

src/burp/JsonJTree.java

@@ -93,10 +93,32 @@ public void actionPerformed(ActionEvent e) {
 			}
 		});
 
+		popup.addSeparator();
+
+		addToPopup(popup, "Collapse full tree", new ActionListener() {
+			public void actionPerformed(ActionEvent e) {
+				collapseChildren(root);
+			}
+		});
+
+		if (node != root) {
+			addToPopup(popup, "Collapse subtree below this node", new ActionListener() {
+				public void actionPerformed(ActionEvent e) {
+					collapseChildren(node);
+				}
+			});
+		}
 
 		popup.show(e.getComponent(), e.getX(), e.getY());
 	}
 
+	private void collapseChildren(DefaultMutableTreeNode node) {
+		final ArrayList<DefaultMutableTreeNode> list = Collections.list(node.children());
+		for (DefaultMutableTreeNode child : list) collapseChildren(child);
+		if (node.isRoot()) return;
+		tree.collapsePath(new TreePath(node.getPath()));
+	}
+
 	private static boolean mayBeJwt(final String value) {
 		return JWT_RE.matcher(value).matches();
 	}