Stream rearchitecture (#126)

* Add generic protocol handler

* Add generic protocol handler to stream muxing pipeline

* Modify conn_handler to only deal with connections

* mplex accept stream architecture changes

* Add create generic protocol handler

* Fix minor bugs

* who would win 4 devs or one not

* Debugging

* rearch with handle_incoming infinite loop, seems to work, needs cleanup"

* passing linting, still needs cleanup

* fixing linting again; code still needs cleanup

* fixing tests; code still needs cleanup

* adding test cleanup and task cleanup, removing prints

* linting, and cleanup complete

* storing connections based on peer id

* remove dead code

* remove unnecessary peer_id

tests/utils.py

@@ -0,0 +1,14 @@
+import asyncio
+
+from contextlib import suppress
+
+
+async def cleanup():
+    pending = asyncio.all_tasks()
+    for task in pending:
+        task.cancel()
+
+        # Now we should await task to execute it's cancellation.
+        # Cancelled task raises asyncio.CancelledError that we can suppress:
+        with suppress(asyncio.CancelledError):
+            await task