New pull list interface taking advantage of flattener for speed,

New pull list interface taking advantage of flattener for speed,

and advanced sorting.  For now, access it by the "Simplifed Pull List"
button along the bottom edge of the existing holds pull list interface
(but I think when/if this thing is widely accepted, it should replace
the existing interface outright).

With thanks to Mike Peters for testing an early version.  Now including
some updates requested by Thomas Berezansky.

[Column picker not quite right]

Signed-off-by: Lebbeous Fogle-Weekley <lebbeous@esilibrary.com>