LP#1301599 TPAC result table accessibility improvements

* Give the main result table a screenreader-only header to describe the
  table columns.
* Set the role=presentation in one of the sub-tables used only for
  layout.

Signed-off-by: Bill Erickson <berick@esilibrary.com>
Signed-off-by: Ben Shum <bshum@biblio.org>
LP#1301599 TPAC advanced search additional labels

Provides a number of labels, primarily for select widgets, in the TPAC
advanced search form for improved accessibility.

Signed-off-by: Bill Erickson <berick@esilibrary.com>
Signed-off-by: Ben Shum <bshum@biblio.org>
LP#1301599 TPAC advanced search from labels

Instead of using titles / aria-labels directly on advanced search
selectors, provide selector IDs so the existing text labels can be
turned into <labels> and linked (by id) to their form control.

This means we only need one label per form control, which improves
usability from an accessibility perspective.

Signed-off-by: Ben Shum <bshum@biblio.org>
LP#1301599 TPAC add missing metabib filter label

In the quick search bar along the top.

Signed-off-by: Bill Erickson <berick@esilibrary.com>
Signed-off-by: Ben Shum <bshum@biblio.org>
LP#1301599 TPAC replace aria-label with title

As appropriate, replace aria-label attributes with traditional HTML
title attributes.

For ref, from the LP entry:

http://www.w3.org/TR/2013/WD-aria-in-html-20131003/#first-rule-of-aria-use

"If you can use a native HTML element [HTML5] or attribute with the
semantics and behaviour you require already built in, instead of
re-purposing an element and adding an ARIA role, state or property to
make it accessible, then do so."

Signed-off-by: Bill Erickson <berick@esilibrary.com>
Signed-off-by: Ben Shum <bshum@biblio.org>
LP#1301599 Additional TPAC facets structure markup

Labeling facets with <h4> tags provides additional page structure for
screen readers in the TPAC results pages.

Signed-off-by: Bill Erickson <berick@esilibrary.com>
Signed-off-by: Ben Shum <bshum@biblio.org>
LP#1301599 Remove duplicate title attributes

Thanks to Ben Shum for spotting these!

Signed-off-by: Bill Erickson <berick@esilibrary.com>
Signed-off-by: Ben Shum <bshum@biblio.org>