Bug 10347 - Deactivate "Add item" button when "Add multiple copies" was activated

Bug 10347 - Deactivate "Add item" button when "Add multiple copies" was activated

When the "Add multiple items" button is pressed the other submit buttons
should be hidden in order to eliminate confusion about which button
submits the form at that stage in the process.

This patch alters the form so that clicking the "add multiple" button
hides the other two buttons and displays form for submitting the number
of copies to add.

This patch also makes changes to accompanying text in order to make
things (hopefully) clearer. The button text has been changed (again, see
Bug 10346) to "Add multiple copies of this item."

Explanatory text has been added "The barcode you enter will be
incremented for each additional item," because that seemed non-obvious
about the process.

Unrelated change: a section of obsolete JavaScript has been removed.

To test, go to the add/edit items page for a new or existing record.
Test adding a single item, adding & duplicating, and adding multiple.
The add multiple form should be shown upon clicking 'add multiple,' and
hidden when 'cancel' is clicked.

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Work as described, tried adding one, one & dup, multiple and cancel multiple
No errors

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Brendan Gallagher <bredan@bywatersolutions.com>