Tqdm

- allow delaying `display()` to a different notebook cell (1059 <- 909, 954)
+ add `notebook` argument `display=True` (use `display=False` with `display(tqdm_object.container)`)
+ add `keras.TqdmCallback` support for initialiser arguments (use `display=False` with `tqdm_callback_object.display()`) (1059 <- 1065)
+ add documentation
- add CI on windows (507)
- enable CI on OSX
- migrate CI Travis => GHA
+ add tests for MacOS & Windows
+ add tests for py3.9 (1073)
+ update documentation
- minify docker build
- update tests
- misc tidy

- add `{eta}` datetime `bar_format` argument (1055 <- 1051)
+ e.g. `bar_format='{l_bar}{bar}| {n_fmt}/{total_fmt} [{rate_fmt} ETA:{eta:%y-%m-%d %H:%M}{postfix}]'`
- fix py3 CLI `--update` & `--update_to`
- replace `nosetests` with `pytest` (1052, 1045)
- add & update tests

- fixed `platform.system()` causing `fork()` warnings (691)
- fixed `contrib.concurrent.process_map` pickling error with `threading.RLock` (920)
- updated documentation & examples
- updated CI framework
- updated tests
- misc code tidy

- fix multiprocessing lock creation leak (982, 936, 759)
+ fixes 617 which introduced this bug (v4.29.0, released 2019-01-06, undiagnosed until now) where multiple threads could concurrently create and append process locks to a global list, then try to release them without first acquiring :imp:
- major test overhaul: fix, update, and speed up
- misc CI framework updates
- code linting
- minor documentation tidy

- add bar `colour` option (1040 <- 450)
+ for `notebook` as well as `std`/CLI
+ plain text as well as hex (e.g. 'green' or '00ff00')
- `notebook` improvements (1032 <- 1031)
+ split bar description into separate widget
+ improve `reset()` (handle width and colour)
- fix exceptions when `file` is closed (1041, 1036 <- 1033)
- add & update tests
- minor documentation updates
- move and configure issue/pr templates

- CLI: add `--tee` (1014 <- 1013)
- CLI: add `--update` and `--update_to` (996 <- 975)
- CLI: add `--null` (996)
- CLI: accept `-` instead of `_` in options (e.g. `--update-to`)
- make `update()` return `True` on `display` to ease efficient use of custom callbacks (845)
- fix `py>=3` CLI `--delim` encoding error
- fix `py>=3.5` version detection in `tqdm.auto` (1029 <- 1028)
- fix final ETA when using `initial` (1021 <- 689)
- update documentation
+ add & update custom callback examples
+ improve help formatting of boolean CLI options
- add & update tests