Tqdm

- add `tqdm.dask.TqdmCallback` (1079, 279 <- 278)
- add `asyncio.gather()` (1136)
- add basic support for `length_hint` (1068)
- add & update tests
- misc documentation updates (1132)
+ update contributing guide
+ update URLs
+ bash completion: add missing `--delay`
- misc code tidy
- add `[notebook]` extra (1135)

- add start `delay` in seconds (836 <- 1069, 704)
- add tests
- misc code tidy (1130)
- misc documentation updates

- add line buffering for `DummyTqdmFile` (960)
- fix & update demo notebook (1127)
- fix py3 urllib examples (1127)
- suppress deprecated `pandas` warnings (824, 1094)
- misc framework updates
- misc tests updates
- misc code tidy

- fix attribute errors when disabled (1126)
+ `reset()` (1125)
+ `unpause()`
- add tests

- fix `repr()` & `format_dict` when disabled (1113 <- 624)
- rename `__repr__()` => `__str__()`
- minor documentation updates (1113)
+ fix Binder demo notebook (1119)
+ remove explicit Dockerfile
+ move some images to external repo
- add & update tests

- add `tqdm.tk` (1006)
- add `tqdm.rich`
- minor formatting improvements for `tqdm.gui`
- fix `display()` inheritance/override
- add tests
- add documentation