Multiple issues related to the Most Active Topics Panel

Issues/tasks related to the panel:

1. The panel doesn't look at all like the other default panels: it doesn't have the same title bar, it's wider than the other panels and you can't expand/collapse it
2. I can't drag & drop it from Administration -> Panel Wizard
3. The title of the panel should be "Most Active Topics" instead of "Discussion Topics"
4. Remove the "TopicTemplate" entry from the panel
5. Remove the "##" that follow the "Topics" text