add encoding parameter to all file open() calls in code samples, example files, and text

examples/plural4.py

@@ -15,7 +15,7 @@ def build_match_and_apply_functions(pattern, search, replace):
     return [matches_rule, apply_rule]
 
 rules = []
-with open('plural4-rules.txt') as pattern_file:
+with open('plural4-rules.txt', encoding='utf-8') as pattern_file:
     for line in pattern_file:
         pattern, search, replace = line.split(None, 3)
         rules.append(build_match_and_apply_functions(

examples/plural5.py

@@ -15,7 +15,7 @@ def build_match_and_apply_functions(pattern, search, replace):
     return [matches_rule, apply_rule]
 
 def rules(rules_filename):
-    with open(rules_filename) as pattern_file:
+    with open(rules_filename, encoding='utf-8') as pattern_file:
         for line in pattern_file:
             pattern, search, replace = line.split(None, 3)
             yield build_match_and_apply_functions(pattern, search, replace)

examples/plural6.py

@@ -18,7 +18,7 @@ class LazyRules:
     rules_filename = 'plural6-rules.txt'
 
     def __iter__(self):
-        self.pattern_file = open(self.rules_filename)
+        self.pattern_file = open(self.rules_filename, encoding='utf-8')
         self.cache = []
         self.cache_index = 0
         return self