Updated submodule references to latest imagen
Restored simplified SheetView implementation till DataViews are ready for use
Updated paramtk submodule reference
Updated paramtk submodule reference
Ignoring *.cpp files generated by Cython
Removed commented code
Added the update_sheet_activity function which updates sheets individually
Merge branch 'master' into pjfranalysis
Removed explicit .gitignore entry for sparse.cpp file