Add 'SnippetTextExtractor' and 'snippetText' field.
Add 'Subject' field.
Add 'path_string' field.
Add 'SlugExtractor' and 'getId' field.
Add 'CreatorExtractor' and 'Creator' field.
Add 'created' field.
Add multicore Solr buildout and use it for development.
Refactor passing of resource infos between phases.
Make 'SitemapParser' take a reference to the 'Site' config

the sitemap was fetched from.
Fetch all sitemaps in advanced, before starting to fetch any resources.
Add membership testing for plain URLs to 'SitemapParser'.
Make `SitemapParser.url_infos` a memoized property.
Add basic 'search' method to 'SolrConnector'.
Add 'unique_field' and 'url_field' attributes to 'Config'.
Implement purging of docs that have been removed from sitemap.
Add 'last_modified_field' attribute to 'Config'.
Add 'HeaderMappingExtractor' and 'portal_type' field.
Make 'Field' bind its extractor to itself.
Make 'Config' bind its fields to itself.
Make 'Config' bind its sites to itself.