redirection convenience

[casperdcl]

• add writelines to contrib.DummyTqdmFile
• add std_out_err_redirect_tqdm to contrib
• continues Add missing isatty() method to DummyTqdmFile #713
• related: Merge to progressbar2 #855

[KOLANICH]

IMHO - classes used for redirection (including progressbar2 ones) should be moved into a separate package.

The things I deeply dislike about the redirection are that:

• it modifies the global state. So we need a refcounting self-destructing singleton to properly support reentrying and multithreading.
• it replaces the object with an own one. And that object doesn't mock sys.stdout well enough. For example it lacks flush. Libs may be using isinstance or using unimplemented details may be broken. But python 3.8 has audit hooks 1 2, I wonder if they can be used for modifying the output to stdout and stderr in a more safe way (without explicitly replacing an object).

[casperdcl]

I agree - and tqdm.contrib is a separate subpackage (part of #855)

[casperdcl]

Btw the new way does wrap everything (incl. flush() and any other members)

[KOLANICH]

tqdm.contrib is a separate subpackage

I mean a separate repo and a separate wheel.