LOKDocView: add part name retrieval.

Change-Id: Iac31de0410d7f6187e5884152c329375047a23f4

include/LibreOfficeKit/LibreOfficeKitGtk.h

@@ -62,7 +62,8 @@ int             lok_docview_get_parts       (LOKDocView* pDocView);
 int             lok_docview_get_part        (LOKDocView* pDocView);
 void            lok_docview_set_part        (LOKDocView* pDocView,
                                              int nPart);
-
+char*           lok_docview_get_part_name   (LOKDocView* pDocView,
+                                             int nPart);
 #ifdef __cplusplus
 }
 #endif

libreofficekit/source/gtk/lokdocview.c

@@ -204,5 +204,8 @@ SAL_DLLPUBLIC_EXPORT void lok_docview_set_part( LOKDocView* pDocView, int nPart)
     renderDocument( pDocView );
 }
 
-
+SAL_DLLPUBLIC_EXPORT char* lok_docview_get_part_name( LOKDocView* pDocView, int nPart )
+{
+    return pDocView->pDocument->pClass->getPartName( pDocView->pDocument, nPart );
+}
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