Add Pycharm's .idea directory to gitignore

[rajathagasthya]

No description provided.

[the-knights-who-say-ni]

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[Carreau]

note you can also set that globally on your system :

$ cat ~/.gitconfig
# This is Git's per-user configuration file.
[core]
	excludesfile = $HOME/.gitignore  

Which allow you to not patch every project you contribute to.

[vstinner]

Compared to the old .hgignore, .gitignore lacks more files:

BuildLog.htm
.DS_Store
Include/pydtrace_probes.h
lcov-report/
Misc/*.wpu
Tools/unicode/build/
Tools/unicode/MAPPINGS/

I don't know these files, so I don't know if it's ok to add them as well.

For .DS_Store (used by macOS): it seems like Git ignores it by default, which is a good idea ;-)

[zware]

We just rejected a patch to add Eclipse's project dir (bpo-29510), so I'm closing this as well.

Thanks for contributing, though!

[zware]

We do probably need to update .gitignore, though.