Fix various Traditional and holds-go-home best-hold sort orders

Fix various Traditional and holds-go-home best-hold sort orders

approx is a more correct determinant to give the behavior sites are used
to.  hprox can cause copies to be too eager to go home when there are
holds with that copy's circ lib as its request lib (if that's what you
want, then you do pick or create a sort-order with hprox near the top).

Address a problem in the copy_has_not_been_home CTE. This expression was
always meant to provide a TRUE or FALSE value as its lone result, but
would return NULL in cases where copies had no transit history.

Also use pickup_lib, not request_lib, as the determinant of
nearness-to-home.  request_lib was used with the thinking that an item's
"owning" patrons should have their wishes favored at holds-go-home time,
even if where they wanted to send the copy was not actually home, but
that's neither necessarily desired nor very intuitive.

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