VisualEditor/Todo list

Tasks

 * ContentEditable
 * Data model sync
 * Fix viewport shift when pasting to off-screen element (Christian)
 * How to handle multiple cursors?
 * IME (Inez)
 * Spellchecker (Inez)
 * ContentEditable and EditSurface
 * Table editing interface
 * Cut/Copy/Paste (Christian)
 * From article (Christian)
 * From external source (sanitize structure) (Christian)
 * Represent lists in hierarchical structure (instead of flat as it is now) (Inez/Trevor)
 * Drag&drop
 * EditSurface
 * IME (Rob)
 * Floating content (Trevor)
 * Right-to-left selection and editing
 * Selection on mobile
 * Match normal page styling
 * Spellchecker
 * Data Model
 * Parser integration
 * Tree sync
 * Attribute operations