VisualEditor/Design/Table editor

This is an important development and should be put high in the priority list.

Table editing is difficult to do well. We want to do well.

Goals

 * Allow users to add a new table and start adding content as quickly as possible.
 * Allow users to edit the table in context, without having to go into lots of menus.

Desired Possible Functionality

 * Create table
 * Delete table
 * Resize table column widths
 * Rows
 * Toggle table cells/table headings
 * Add row before
 * Add row after
 * Duplicate row
 * Reorder rows (drag sort)
 * Delete row
 * Columns
 * Toggle table cells/table headings
 * Add column before
 * Add column after
 * Duplicate column
 * Reorder columns (drag sort)
 * Delete column
 * Cells
 * Toggle table cell/table heading
 * Merge right
 * Merge left
 * Merge up
 * Merge down
 * Split into rows
 * Split into columns
 * Change background color (highlight) (eg. World Series Most Valuable Player Award)
 * Right-, left-, and center-aligned content
 * Any element
 * edit style and attributes of the element