jinja2: Add Template.environment (#1789)

From the docstring for Template: "Template objects created from the
constructor rather than an environment do have an `environment`
attribute that points to a temporary environment ..."

Author: srittau

third_party/2and3/jinja2/environment.pyi

@@ -79,6 +79,7 @@ class Environment:
 
 class Template:
     def __new__(cls, source, block_start_string: Any = ..., block_end_string: Any = ..., variable_start_string: Any = ..., variable_end_string: Any = ..., comment_start_string: Any = ..., comment_end_string: Any = ..., line_statement_prefix: Any = ..., line_comment_prefix: Any = ..., trim_blocks: Any = ..., lstrip_blocks: Any = ..., newline_sequence: Any = ..., keep_trailing_newline: Any = ..., extensions: Any = ..., optimized: bool = ..., undefined: Any = ..., finalize: Optional[Any] = ..., autoescape: bool = ...): ...
+    environment: Environment = ...
     @classmethod
     def from_code(cls, environment, code, globals, uptodate: Optional[Any] = ...): ...
     @classmethod