typing: Convert function type annotations to Python 3 style.

Generated by com2ann (slightly patched to avoid also converting
assignment type annotations, which require Python 3.6), followed by
some manual whitespace adjustment, and two fixes for use-before-define
issues:

-    def set_zulip_client(self, zulipToJabberClient: ZulipToJabberBot) -> None:
+    def set_zulip_client(self, zulipToJabberClient: 'ZulipToJabberBot') -> None:

-def init_from_options(options: Any, client: Optional[str] = None) -> Client:
+def init_from_options(options: Any, client: Optional[str] = None) -> 'Client':

Signed-off-by: Anders Kaseorg <anders@zulipchat.com>

zulip/setup.py

@@ -10,8 +10,7 @@ import itertools
 with open("README.md") as fh:
     long_description = fh.read()
 
-def version():
-    # type: () -> str
+def version() -> str:
     version_py = os.path.join(os.path.dirname(__file__), "zulip", "__init__.py")
     with open(version_py) as in_handle:
         version_line = next(itertools.dropwhile(lambda x: not x.startswith("__version__"),
@@ -19,8 +18,7 @@ def version():
     version = version_line.split('=')[-1].strip().replace('"', '')
     return version
 
-def recur_expand(target_root, dir):
-    # type: (Any, Any) -> Generator[Tuple[str, List[str]], None, None]
+def recur_expand(target_root: Any, dir: Any) -> Generator[Tuple[str, List[str]], None, None]:
     for root, _, files in os.walk(dir):
         paths = [os.path.join(root, f) for f in files]
         if len(paths):