Replace progressbar2 by tqdm

[chaozg]

fixed #501

Issue:

progressbar2 has display issues in jupyter notebooks where its progress information can easily span several pages. For example, sampler.sample(200) will give a screen output like the following

  0% (0 of 200) |                        | Elapsed Time: 0:00:00 ETA:  --:--:--
  0% (1 of 200) |                        | Elapsed Time: 0:00:00 ETA:   0:00:28
  2% (4 of 200) |                        | Elapsed Time: 0:00:00 ETA:   0:00:14
  2% (5 of 200) |                        | Elapsed Time: 0:00:00 ETA:   0:00:36
  3% (6 of 200) |                        | Elapsed Time: 0:00:01 ETA:   0:00:39
  3% (7 of 200) |                        | Elapsed Time: 0:00:01 ETA:   0:00:36
  4% (8 of 200) |                        | Elapsed Time: 0:00:01 ETA:   0:00:36
  5% (10 of 200) |#                      | Elapsed Time: 0:00:01 ETA:   0:00:29
  5% (11 of 200) |#                      | Elapsed Time: 0:00:01 ETA:   0:00:29

... many lines of display, omitted here (note by Charlie)

 97% (194 of 200) |##################### | Elapsed Time: 0:00:35 ETA:   0:00:00
 97% (195 of 200) |##################### | Elapsed Time: 0:00:35 ETA:   0:00:00
 98% (196 of 200) |##################### | Elapsed Time: 0:00:35 ETA:   0:00:00
 98% (197 of 200) |##################### | Elapsed Time: 0:00:35 ETA:   0:00:00
 99% (198 of 200) |##################### | Elapsed Time: 0:00:35 ETA:   0:00:00
 99% (199 of 200) |##################### | Elapsed Time: 0:00:36 ETA:   0:00:00
100% (200 of 200) |######################| Elapsed Time: 0:00:36 Time:  0:00:36

Solution:

tqdm is a package that works similarly to progressbar2 but does not suffer the above-described display problem.

With tqdm, the same line displaying the progress information will be dynamically updated (as expected).

100%|██████████| 200/200 [00:02<00:00, 68.48it/s]

[nabriis]

LGTM. tqdm looks like a better package. Also has no dependencies.

[chaozg]

LGTM. tqdm looks like a better package. Also has no dependencies.

Great, now I'm requesting @jakobsj 's review 😄

[jakobsj]

Looks good, thanks!