Add natural_list

[akshaybabloo]

• This PR adds natural_list to convert a list of items into a comma separated sentence with and at the last.
• I have also ignored .idea/* folder

closes#103

[codecov]

Codecov Report

Merging #110 (14d76fb) into main (7e20f6e) will decrease coverage by 0.78%.
The diff coverage is 100.00%.

@@ Coverage Diff @@## main #110 +/- ##
==========================================
- Coverage 99.06% 98.28% -0.78% 
==========================================
Files 9 11 +2 Lines 745 759 +14 ==========================================
+ Hits 738 746 +8 - Misses 7 13 +6 

Flag	Coverage Δ
macos-latest	96.70% <100.00%> (-1.15%)	⬇️
ubuntu-latest	96.70% <100.00%> (-1.15%)	⬇️
windows-latest	95.25% <100.00%> (-0.72%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/humanize/__init__.py	81.81% <100.00%> (-18.19%)	⬇️
src/humanize/lists.py	100.00% <100.00%> (ø)
tests/test_lists.py	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

[akshaybabloo]

Could you please run the CI again? Thanks.

[hugovk]

Thanks for the PR! I've made some updates, and because this is a new API, added an underscore to the function.

(I'm considering adding underscores to the others too, and having the non-underscore ones be aliases. If so, no need to remove or deprecate the old ones, at least not for a long time.)