Refactor the kittens tui loop to use asyncio

Gets us timers and various jobs for free, and makes it easier to
integrate with libraries that use asyncio from the larger python
ecosystem.

kittens/tui/handler.py

@@ -10,14 +10,19 @@ class Handler:
 
     image_manager_class = None
 
-    def _initialize(self, screen_size, quit_loop, wakeup, start_job, debug, image_manager=None):
-        self.screen_size, self.quit_loop = screen_size, quit_loop
-        self.wakeup = wakeup
+    def _initialize(self, screen_size, term_manager, schedule_write, tui_loop, debug, image_manager=None):
+        self.screen_size = screen_size
+        self._term_manager = term_manager
+        self._tui_loop = tui_loop
+        self._schedule_write = schedule_write
         self.debug = debug
-        self.start_job = start_job
         self.cmd = commander(self)
         self.image_manager = image_manager
 
+    @property
+    def asyncio_loop(self):
+        return self._tui_loop.asycio_loop
+
     def add_shortcut(self, action, key, mods=None, is_text=False):
         if not hasattr(self, '_text_shortcuts'):
             self._text_shortcuts, self._key_shortcuts = {}, {}
@@ -38,7 +43,6 @@ class Handler:
         self.initialize()
 
     def __exit__(self, *a):
-        del self.write_buf[:]
         del self.debug.fobj
         self.finalize()
         if self.image_manager is not None:
@@ -53,8 +57,11 @@ class Handler:
     def on_resize(self, screen_size):
         self.screen_size = screen_size
 
+    def quit_loop(self, return_code=None):
+        self._tui_loop.quit(return_code)
+
     def on_term(self):
-        self.quit_loop(1)
+        self._tui_loop.quit(1)
 
     def on_text(self, text, in_bracketed_paste=False):
         pass
@@ -71,12 +78,6 @@ class Handler:
     def on_eot(self):
         pass
 
-    def on_wakeup(self):
-        pass
-
-    def on_job_done(self, job_id, job_result):
-        pass
-
     def on_kitty_cmd_response(self, response):
         pass
 
@@ -86,7 +87,7 @@ class Handler:
     def write(self, data):
         if isinstance(data, str):
             data = data.encode('utf-8')
-        self.write_buf.append(data)
+        self._schedule_write(data)
 
     def print(self, *args, sep=' ', end='\r\n'):
         data = sep.join(map(str, args)) + end