Fix import in `inprocess_qtconsole.py`

This PR fixes an import error in `docs/examples/frontend/inprocess_qtconsole.py`, but even so, I get this error when running it:

```
Traceback (most recent call last):
  File "inprocess_qtconsole.py", line 58, in <module>
    main()
  File "inprocess_qtconsole.py", line 33, in main
    km.start_channels()
AttributeError: 'QtInProcessKernelManager' object has no attribute 'start_channels'
```
Has `examples/inprocess/embedded_qtconsole.py` superceded this example script? It's the only file in the `docs/examples` tree. Should that whole tree be deleted?