fix #30: enforce utf-8 encoding

since windows used non-utf8-encoding

utils.py

@@ -59,7 +59,7 @@ def remove_dir_with_files(dir):
 
 def read_csv(filename):
     """Returns a list of lines."""
-    with open(filename, "r", newline='') as infile:
+    with open(filename, "r", encoding="utf-8", newline='') as infile:
         lines = []
         reader = csv.reader(infile)
         for line in reader:
@@ -78,7 +78,7 @@ def read_csv_str(str):
 
 def read_json(filename):
     """Returns a list or a dictionary."""
-    with open(filename, "r") as infile:
+    with open(filename, "r", encoding="utf-8") as infile:
         return json.load(infile)
 
 
@@ -89,7 +89,7 @@ def read_json_str(str):
 
 def read_file_to_list(filename):
     """Returns a list of lines."""
-    with open(filename, "r") as infile:
+    with open(filename, "r", encoding="utf-8") as infile:
         return infile.readlines()