A few menu display tweaks

This pull request includes:

• a few adjustments to the CSS to make the look for mouse (as opposed to keyboard) users more consistent with the current MathJax menu without interfering with the keyboard usage (I hope).

  • The focus outline is not shown if the menu is opened by mouse (but focus is still set).
  • The focus outline is not shown for dialog boxes opened by mouse (but focus is still set).
  • The focus outline is not shown for close buttons when clicked by mouse
  • The focus is not shown on the math element after a menu or dialog is closed by mouse click (but is if it is closed by keyboard action).

  So the only significant difference for mouse users from the current UI is that clicking on a math element focuses it and shows the focus outline. (Note that we probably need to implement something for <maction> elements so that they can get the focus and be activated by keyboard and screen reader users. I also haven't checked href's within the math to see if they are accessible.)

• Localization of the "Close Window" string that is used on the close buttons (though I'm wondering if this would be better as "Close Dialog" or "Close Pop-up" since it is not actually the window that is being closed).

• A fix that makes sure aria- and role attributes show up as actual attributes in the DOM.

• A fix to HTML-CSS so that the focus highlighting will be full width when the math is full width (e.g., when there is a \tag, or with percentage-width tables, or with the multline environment).

• Fixes for handling of keyboard and menus in IE < 9.

• Fix so that SVG elements won't be focusable in IE.

• Fix Error jax so that [Math Processing Error] elements work with keyboard menus.