Merge unstable into master

Changes: 
- ability to combine more than one metadata field per facet
- Rewrite the web resources handler: it should now work even with permissions issues, defaulting to sending all separate resources. If a custom report has been created, it will use the concordance resources as a default.
- TOC has been rewritten: no AJAX call for the TOC report. 
- TOC Ajax call for the left sidebar must now generate the HTML from Javascript, and not from inside the CGI script. 
- Remove all function calls from concordance, kwic, object, bibliography reports. This is also the first step towards having an API that exposes the exact same information as the Web UI.
- Move concordance/kwic switcher to the scripts directory, where it belongs. I'm also now using the new concordance and kwic results objects.