Bug 10317: improve display when order receiving page is given an invalid invoiceid

This patch fixes some things on the order receiving/parcel page.

1/ Removes dead code
2/ Displays an error message if invoiceid is unset or does not refer to an
invoice
3/ Fixes a bug in the note ("change note" and "add note" links)

Test plan:
1/ Try to call the invoice page with an existing invoiceid and check
that order results are consistent.
2/ Try without invoiceid or a bad invoiceid and check that an error
message is displayed.
3/ Add and change notes.

Signed-off-by: Cedric Vita <cedric.vita@dracenie.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Works nicely for all tests done.
- parcel.pl with invalid invoicenumber gives a nice error message
- parcel.pl with a valid invoicenumber looks normal
- changing and editing order notes works well

Passes QA script.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Bug 10390: Add ability to delete empty invoices

There is currently no way to delete unused invoices (for example,
invoices created by mistake), and there really should be, since errors
and absent-mindedness can result in numerous empty invoices over the
course of years.

To test:
1) Apply patch.
2) Create three invoices in the Acquisitions module. For one of them,
   receive at least one item. For the other two, do not receive any
   items.
3) View one of the invoices that does not have any items on it.
4) Try to delete it. This should succeed.
5) View the invoice that has an item. There should not be any option
   to delete it.
6) Do an invoice search that brings up the other invoice with no items
   on it. Try to delete it from the results page. This should succeed.
7) Run the unit test:
   > prove t/Acquisition/Invoice.t
8) Sign off.

Signed-off-by: Srdjan <srdjan@catalyst.net.nz>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
All tests and QA script pass. I also did another test:

I cancelled all receipts from an existing invoice and then could
successfully delete it in the last step.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Bug 10390: (follow-up) correct description of a test

Signed-off-by: Galen Charlton <gmc@esilibrary.com>