[composer] Initial groundwork for multiframe table item (Sponsored

by City of Uster, Switzerland)

src/app/CMakeLists.txt

@@ -114,6 +114,7 @@ SET(QGIS_APP_SRCS
   composer/qgsattributeselectiondialog.cpp
   composer/qgscomposer.cpp
   composer/qgscomposerarrowwidget.cpp
+  composer/qgscomposerattributetablewidget.cpp
   composer/qgscomposerhtmlwidget.cpp
   composer/qgscomposeritemwidget.cpp
   composer/qgscomposerlabelwidget.cpp
@@ -253,6 +254,7 @@ SET (QGIS_APP_MOC_HDRS
   composer/qgsattributeselectiondialog.h
   composer/qgscomposer.h
   composer/qgscomposerarrowwidget.h
+  composer/qgscomposerattributetablewidget.h
   composer/qgscomposerhtmlwidget.h
   composer/qgscomposeritemwidget.h
   composer/qgscomposerlabelwidget.h