tqdm v4.49.0 stable

• 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