refactor: pycode: Use OrderedDict to store variable comments

It is worthy to keep the order of analyzer.attr_docs to generate
document in reproducible. So this uses OrderedDict explicitly to do
that. It also helps python3.5 environment.

sphinx/pycode/__init__.py

@@ -11,6 +11,7 @@
 import re
 import tokenize
 import warnings
+from collections import OrderedDict
 from importlib import import_module
 from inspect import Signature
 from io import StringIO
@@ -156,7 +157,7 @@ class ModuleAnalyzer:
             parser = Parser(self.code, self._encoding)
             parser.parse()
 
-            self.attr_docs = {}
+            self.attr_docs = OrderedDict()
             for (scope, comment) in parser.comments.items():
                 if comment:
                     self.attr_docs[scope] = comment.splitlines() + ['']

sphinx/pycode/parser.py

@@ -12,6 +12,7 @@ import itertools
 import re
 import sys
 import tokenize
+from collections import OrderedDict
 from inspect import Signature
 from token import NAME, NEWLINE, INDENT, DEDENT, NUMBER, OP, STRING
 from tokenize import COMMENT, NL
@@ -228,7 +229,7 @@ class VariableCommentPicker(ast.NodeVisitor):
         self.context = []               # type: List[str]
         self.current_classes = []       # type: List[str]
         self.current_function = None    # type: ast.FunctionDef
-        self.comments = {}              # type: Dict[Tuple[str, str], str]
+        self.comments = OrderedDict()   # type: Dict[Tuple[str, str], str]
         self.annotations = {}           # type: Dict[Tuple[str, str], str]
         self.previous = None            # type: ast.AST
         self.deforders = {}             # type: Dict[str, int]