Misc Memory Leaks

[shemnon]

• BasicPopupPanelUI holds on to the last traced frame in a static field, leaking memory
• BasicCommandPopupMenuUI adds a listener when it should be removing a listener on dispose

[IvanRF]

So, for the second point: BasicCommandPopupMenuUI.java#L508 should be:

PopupPanelManager.defaultManager().removePopupListener(this.popupListener);