[Koha] Sending orders by email

[Edgar Fuß]

I've written a patch that may possibly serve as a base for including support into Koha's Acquisition module to send orders to booksellers by email.
See bug 5260, http://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=5260.
Comments welcome. Note that this is just a preliminary version, more or less a proof-of-concept for evaluating the use of Koha for acquisitions at our library.