Table floating toolbar removed, and background colour added.

Background colour button

By default, the rich text editor, tinymce, was putting up a floating toolbar for managing tables. The problem was it often plonked it right where you were editing. All the functions on that menu are available from the tables section of the main toolbar, so I have remove that annoying floating toolbar altogether.

Also, there is now a text background colour button on the toolbar, alongside the text colour button. While this can be generally useful, the main problem was that if you managed to paste text which already had a background the only way to get rid of it previously was to edit the raw HTML.