Update `check_connection` method

In two python example provided in the repository we can observe a similar pattern for the connection checking:

    startup_sec = 1
    while not viz.check_connection() and startup_sec > 0:
        time.sleep(0.1)
        startup_sec -= 0.1
    assert viz.check_connection(), 'No connection could be formed quickly'

I wonder whether this could not be integrated directly to check_connection method without asking the user to write such loop.

What do you think ?

Thanks

[vfdev-5]

@JackUrb tested the master and have no more problems with runing the demo.py as reported in the previous comment.

I looked the PR, looks good to me 😃

[JackUrb]

Implemented in #460