Closes python#28

This change adds `nitpicky=True` (which is an equivalent of `-n`) to
make Sphinx emit warnings for any references to non-existing targets.
Then, it adds `-W` to make it fail whenever a single warning is seen.
Finally, `--keep-going` allows Sphinx to print out all the warnings
before exiting instead of showing just one and bailing.

Resolves python#29

Refs:
* https://www.sphinx-doc.org/en/master/man/sphinx-build.html#cmdoption-sphinx-build-n
* https://www.sphinx-doc.org/en/master/man/sphinx-build.html#cmdoption-sphinx-build-W
* https://www.sphinx-doc.org/en/master/man/sphinx-build.html#cmdoption-sphinx-build-keep-going

This reverts commit 590e99a.

31: Only warn in file init r=ltratt a=nanjekyejoannah

Fixes python#29 

Co-authored-by: Joannah Nanjekye <[email protected]>

* PEP-7 for import.c

* re-order imports

* fix tests

* some final nits

* alter other file

* alter sysmodule.c

Add the unicodedata.iter_graphemes() function to iterate over grapheme
clusters according to rules defined in Unicode Standard Annex #29.

Add unicodedata.grapheme_cluster_break(), unicodedata.indic_conjunct_break()
and unicodedata.extended_pictographic() functions to get the properties
of the character which are related to the above algorithm.

Co-authored-by: Guillaume "Vermeille" Sanchez <[email protected]>

Add the unicodedata.iter_graphemes() function to iterate over grapheme
clusters according to rules defined in Unicode Standard Annex #29.

Add unicodedata.grapheme_cluster_break(), unicodedata.indic_conjunct_break()
and unicodedata.extended_pictographic() functions to get the properties
of the character which are related to the above algorithm.

Co-authored-by: Guillaume "Vermeille" Sanchez <[email protected]>

…H-143076)

Add the unicodedata.iter_graphemes() function to iterate over grapheme
clusters according to rules defined in Unicode Standard Annex python#29.

Add unicodedata.grapheme_cluster_break(), unicodedata.indic_conjunct_break()
and unicodedata.extended_pictographic() functions to get the properties
of the character which are related to the above algorithm.

Co-authored-by: Guillaume "Vermeille" Sanchez <[email protected]>