[XWIKI-1390]: "Sample mode" for PanelWizard

I was talking to Vincent about this on IRC, and he suggested that I open a jira issue, and send an email to the list, so here it is. When loading the PanelWizard against a fairly large XWiki, the page can take a fairly long time to load. Vincent and I talked about a few approaches: Adding a "Sample mode" field to the Panels, where the panels would render themselves w/ sample/dummy data to avoid queries to the DB. The PanelWizard would then have to somehow display these panels in "sample" mode. The other is to skip rendering of all of the panels entirely: list the title, links to edit/delete and provide a some kind of new button to "display panel" or "display panel contents", which would defer panel loading until requested... This collapsed view would apply to the drag-n-drop off to the sidebars as well... Thoughts? -- 'Waste of a good apple' -Samwise Gamgee