Acq: several interface improvements

Acq: several interface improvements

Several usability improvements throughout Acq, including:

  * A logical re-ordering of the main "actions" dropdown in several Acq
    interfaces (selection lists, purchase orders, acq search results, MARC
    federated search interface, etc).
  * "Actions" dropdown also has its options enabled/disabled depending what
    interface you're seeing it through, and redundant entries are
    removed from the per-lineitem secondary dropdown.
  * Add to Purchase Order dialog added to "actions" dropdown
  * Middle layer support for adding many line items to a PO at once
  * Create/add to Purchase Order operations can no longer steal line
    items from current POs
  * Create invoice from / link to invoice now work in new tab
  * Receive/unreceive now by selected lineitem instead of whole PO
  * Claim policy application works more simply now
  * Invoices interface auto-populates "# Invoiced" column with number of
    invoicable copies, and copies the "billed cost" column to the
    "amount paid" column if the latter doesn't have anything in it yet.
  * You can now only cancel specific lineitems when they're actually on
    a PO and have the state of 'on-order'.
  * Avoid double-activation of POs at UI level
  * Disable invoice and cancel options for whole pending POs
  * Disable zero-copy checkbox for activated POs
  * Disable new misc charges (acq.invoice_item) for activated POs

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