Makes more sense now that we have different types of trees.

- Removed needless required classes from Viewport.
- videos/guides/examples Index classes now require their own List.
- Not using Ext.create('Ext.XTemplate') at class definition time.

- Add doc-comments to all classes.
- Add missing semicolons, remove trailing commas.
- Use Ext.Array.forEach instead of strange for-loop.
- Use === instead of ==.
- Rmove some commented-out code.
- Several other code style improvements.

It's now done by Guides class method #to_tree.

Don't auto-detect type and default value when documented config/property
name doesn't match up with name from code.