* include/Makefile.am,
include/Operation.h,
include/Win_GParted.h,
src/GParted_Core.cc,
src/Makefile.am,
src/Win_GParted.cc,
include/OperationCheck.h (new),
src/OperationCheck.cc (new): added 'check' operation. The
functionality was already there, but it was not possible yet to
activate it from the gui.