Can not invoke hunter-trace multiple times

[vitrun]

What I did

1. Start a long running script by python demo.py：

   
   import os
   import time

from hunter import remote remote.install(verbose=False)

while True: print(os.path.join('a', 'b')) time.sleep(1)

2. Invoke `hunter-trace -p THE-PID-OF-ABOVE-SCRIPT` 
It worked as expected：
```text
[...]nvs/py38/lib/python3.8/posixpath.py:83    line         if b.startswith(sep):
[...]nvs/py38/lib/python3.8/posixpath.py:85    line         elif not path or path.endswith(sep):
[...]nvs/py38/lib/python3.8/posixpath.py:88    line         path += sep + b
[...]nvs/py38/lib/python3.8/posixpath.py:82    line         for bin map(os.fspath, p):
[...]nvs/py38/lib/python3.8/posixpath.py:92    line         return path
[...]nvs/py38/lib/python3.8/posixpath.py:92    return    <= join: 'a/b'

3. Stop the trace client by CTRL-C
4. Re do step-2 Oops. It complains:

   Failed to activate: AttributeError("'_io.TextIOWrapper' object has no attribute 'get'"). No tracer options.

What I expect

It should be able to re-enter the tracer via client

[vitrun]

It seems that deactivate in remote.py is to blame:

def deactivate():
    hunter._default_config = sys.stderr
    hunter.stop()

It should be hunter._default_config = {}?

[ionelmc]

Gonna release 3.5.1 today if possible.

[ionelmc]

Released now on pypy.