Replace comments with descriptive method names.

Add SGBubbleTableViewAdapter
-contentCellForBubbleTableView:withBubbleData:
-headerCellForBubbleTableView:withBubbleData:
-typingCellForBubbleTableView:
Make it build on non-ARC.
Use 4-space tabs.
Use ARC in the example project.

I'm going to gradually remove the manual retain/release code.
Protocols can conform to other protocols! Simplify!
Rename NSBubbleTypingType -> SGBubbleTypingDirection.
Replace some -objectAtIndex: with literal syntax.
Rename SGBubbleData-avatar to -avatarImage.
Use named constants instead of inline integers.
Update example ViewController.

* Replace direct ivar access with properties
* Replace directly sending -resignFirstResponder with UIView-endEditing:
* Replace objectAtIndex with literal syntax
* Extract static bubble data init into -staticBubbleData