RFC : Better statistics about acquisitions

This RFC re-makes /report/acquisitions_stats.pl The goal would be to be able to use this tool to follow acquisitions practices by librarians. This RFC speculates that 2 authorized values fields will be added to a budget (see RFC: refining the budgets hierarchy and informations).

Two things are separated out: filters to select the information; definition of a visualization by the librarian.

Filters. The following filters can be used (at once):

• order date : from date; to date
• reception date : from date; to date
• library branch
• localisation
• vendor
• librarian login
• budget
• budget authorized value #1
• budget authorized value #2

Visualization. Once the set of data is filtered, one can select informations to be shown in the report:

• all of the above (from order date to budget authorized value #2)
• short bibliographic informations
• call number
• location
• item type
• price

Koha still, as it does, lets the user choose between screen and csv output.