BibCirculation: patron-driven acquisition and more

* Implementation of patron driven acquisition
  of newly released print books.

* Purchase option to all books for the user.

* Handling groups of similar 'Item's having the
  same 'description' and belonging to the same
  record while issuing loans (multi-volume books etc).

* Automatic and manual recalls of ILLs on the
  lines of normal loans.

* Rectifies error arising when registering a user.
  (closes #1280)

* Other changes involving admin interfaces, code
  reshuffling, refactoring and clean-up.

Tested-by: Tibor Simko <tibor.simko@cern.ch>
BibCirculation: admin guide cleanup