#VUFIND-972

Changing method signature from
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public function getHolding($id, $patron = false)
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to
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public function getHolding($id, array $patron = null)
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This change allows the code to match the documentation, and makes the signature type restrictive which reduces confusion. Since a bool is not an array we have to change $patron = false to $patron = null, which is allowed.

Impacts beyond the simple signature change are small changes to Aleph.php, Demo.php and Holds.php
Fixed bug -- wrong variable name.
Fixed various notices.