add a command to display images in NPC windows
All of the following are equivalent:
showimage("guiicons/flags/en");
showimage("graphics/guiicons/flags/en");
showimage("/graphics/guiicons/flags/en.png");
All of the following are equivalent:
showimage("guiicons/flags/en");
showimage("graphics/guiicons/flags/en");
showimage("/graphics/guiicons/flags/en.png");