Clean-up Sources and Citations views:

* Add icon for citations view
* disable old sourceview
* change citationtreeview to be Sources navigation view
* citationlistview is now the Citations view
* merge libcitationview into citationlistview and citationtreeview, and corrected and rationalised
* remove libcitationview
* corrected initialisation of source_handle in Citation.py
* fixes for preventing same source being edited twice
    - fixed blockedtext in citationembededlist
    - override build_window_key in editcitation.py

svn: r18211

src/images/scalable/Makefile.am

@@ -19,6 +19,7 @@ dist_pkgdata_DATA = \
 	gramps-bookmark-edit.svg \
 	gramps-bookmark-new.svg \
 	gramps-bookmark.svg \
+	gramps-citation.png \
 	gramps-config.svg \
 	gramps-date-edit.svg \
 	gramps-date.svg \