* implement new Utils get_source_and_citation_referents
* Update sourceview.py and citationtreeview.py to use it
* Fix editsource.py, where deletion of a source object was not properly dealing with all possible citations
* Update mediaobj.py which still had a remnant of a source_list
* fix _HasTextMatchingSubstringOf filter to deal with text in both sources and citations
svn: r18394
* Changed database to introduce Citations
* Introduced new Citation Primary object and CitationBase (equivalent to CitationRef) child object
* Implemented CitationTreeModel and CitationListModel
* Implemented CitationTreeView and CitationListView for new citation views in the navigator
* Implemented EditCitation which is used both for the citation views in the navigator and for the citations of an object
* Implemented the CitationEmbedList to display the citations of an object
* Modified the bottom bar gramplets to support citations
* Implemented the citation selector.
* Modified Media object to include references to Citations
* Initial work on deleting citations
svn: r17960
Start with reuse of preferences for all configuration
Allow all view plugins to set configuration dialog
TODO: activate the column reorder in config of listviews
svn: r14176