Large patch: Renamed project and added functionnalities

Hi,

This is a large patch for three things: 
- Renamed project from "generic xml importer" to the simpler "xml import" (this is easy to say, but implies lot of changes), 
- Added choice of a XSLT sheet,
- Added possibility to import multiple files, specially useful when the xml format manages only one record.
 
Sincerely,

Daniel Berthereau
Infodoc & Knowledge management