Refactor application of NNC / EDITNNC

- The edit manipulations from EDITNNC have already been applied to the NNC data
  from opm-common

- The NNC data structures are guaranteed to be ordered, both with cell1 <= cell2
  and the NNCs are in ascending order

- The NNC output to EGRID / INIT files is based on std::vector<NNCdata>

CMakeLists_files.cmake

@@ -23,7 +23,6 @@
 # originally generated with the command:
 # find opm -name '*.c*' -printf '\t%p\n' | sort
 list (APPEND MAIN_SOURCE_FILES
-  ebos/nncsorter.cpp
   opm/core/props/satfunc/RelpermDiagnostics.cpp
   opm/simulators/timestepping/SimulatorReport.cpp
   opm/simulators/flow/MissingFeatures.cpp
@@ -83,7 +82,6 @@ list (APPEND TEST_SOURCE_FILES
   tests/test_vfpproperties.cpp
   tests/test_milu.cpp
   tests/test_multmatrixtransposed.cpp
-  tests/test_nncsorter.cpp
   tests/test_wellmodel.cpp
   tests/test_deferredlogger.cpp
   tests/test_timer.cpp