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/integrations/svn/zulip_svn_config.py

@@ -18,8 +18,7 @@ ZULIP_API_KEY = "0123456789abcdef0123456789abcdef"
 # and "my-super-secret-repository" repos to
 # * stream "commits"
 # * topic "branch_name"
-def commit_notice_destination(path, commit):
-    # type: (Text, Text) -> Optional[Dict[Text, Text]]
+def commit_notice_destination(path: Text, commit: Text) -> Optional[Dict[Text, Text]]:
     repo = path.split('/')[-1]
     if repo not in ["evil-master-plan", "my-super-secret-repository"]:
         return dict(stream  = "commits",