Added example for merging two namelists

examples/merge_NEMO_namelists.py

+from context import namelist
+
+in_file_ref = "namelist_ref"
+in_file_cfg = "namelist_cfg"
+
+with open(in_file_ref) as f:
+    ref_nmls = namelist.parse_namelist_file(f)
+
+with open(in_file_cfg) as f:
+    cfg_nmls = namelist.parse_namelist_file(f)
+
+nmls = ref_nmls.copy()
+
+for k in cfg_nmls:
+    if k in nmls:
+        nmls[k].update(cfg_nmls[k])
+    else:
+        nmls[k] = cfg_nmls[k]
+
+for nml in nmls:
+    print(str(nmls[nml]))