Allow hiding the progress bar for very fast loops (feature request)

[anntzer]

• I have visited the source website, and in particular
  read the known issues
• I have searched through the issue tracker for duplicates
• I have mentioned version numbers, operating system and
  environment, where applicable:

  import tqdm, sys
  print(tqdm.__version__, sys.version, sys.platform)

  4.31.1 3.7.2 (default, Dec 29 2018, 06:19:36) 
  [GCC 7.3.0] linux
  

Qt's QProgressDialog implements the minimumDuration property (https://doc.qt.io/qt-5/qprogressdialog.html#minimumDuration-prop) which is documented as follows:

This property holds the time that must pass before the dialog appears
If the expected duration of the task is less than the minimumDuration, the dialog will not appear at all. This prevents the dialog popping up for tasks that are quickly over. For tasks that are expected to exceed the minimumDuration, the dialog will pop up after the minimumDuration time or as soon as any progress is set.
If set to 0, the dialog is always shown as soon as any progress is set. The default is 4000 milliseconds.

I believe this would be a nice feature to have in tqdm as well (obviously its default value would have to be zero for backcompat).