Improve information in Sitecore Tab

[kevinobee]

1. distinction between standard fields and user-created fields
2. in visualization, when showing information on renderings - provide a link to the information in the def item of the component. Why? Certain defaults, caching, etc. can be defined there. Also this will say what type of component it is, and where to find the corresponding file.
3. Renderings - I would hide uniqueID - not very useful - only used to be able to generate layout deltas properly
4. Enable "debugging" mode, which would show statistic info on each component (mostly time). Sitecore is already tracking this - maybe it can be fished out.
5. Add Sitecore.Context.PageMode info

[kevinobee]

Add in support for logged in users, license info, sitecore version etc