KM3NeT Dataformat data writeout

Write the offline format output based on the km3net_dataformat package and remove AAnet.

km3buu/tests/test_output.py

@@ -32,7 +32,7 @@ try:
         libpath = Config().km3net_lib_path
     KM3NET_LIB_AVAILABLE = (ROOT.gSystem.Load(join(libpath,
                                                    "libKM3NeTROOT.so")) == 0)
-except ImportError:
+except ModuleNotFoundError:
     KM3NET_LIB_AVAILABLE = False