Use Github Actions for smoke tests

to generate scripts

run buildout and check which files are downloaded
and which eggs are installed

Fix simple typo: expecially -> especially

Fixes #484.

Fix typo.

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Avoid DeprecationWarning: 'U' mode is deprecated (Version 2)

Now the deprecation warning itself is fixed, we no longer need to
suppress it to have the tests pass.

Add a RENormalizer so the easy_install.txt will be happy with scripts
generated on Python 2 (using open(..., 'U')) and on Python 3 (using just
open(...)).

This was suggested by @sallner.

Python 3.7 began warning about open's 'U' mode. Universal newline mode (newline=None) is default in Python 3 so avoid specifying it on Python 3.

Update Trove classifiers and URL

- update list of supported python versions
- point to github instead of the old cheeseshop site

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document query command

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add a `query` command

as suggested by @leorochael

for continuous integration

Typo fix: 'uuinstall' to 'uninstall' in comment

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debugger: Exit with error code on debugged error

When buildout encounter an error, program exists with error code 1, this
should also be the case when exiting from a debugger session when
running with -D option.

Closing #464

Fix most Deprecation and Resource warnings.