`Default_Ignorable_Code_Point`s should all be zero-width

[Jules-Bertholet]

From https://www.unicode.org/faq/unsup_char.html#3:

All default-ignorable characters should be rendered as completely invisible (and non advancing, i.e. “zero width”), if not explicitly supported in rendering.

However, this library incorrectly considers some of them, for example U+3164 HANGUL FILLER, to have non-zero width.

(There is one exception, where this library is correct in assigning a non-zero width to a Default_Ignorable_Code_Point: U+115F HANGUL CHOSEONG FILLER is meant to be combined with other Hangul jamo to form a width-2 syllable block, so it should be assigned width 2 even though it has no display on its own.)

[jquast]

Thanks, I think this is the same as your other issue, that if I am able to distinguish Default_Ignorable_Code_Point values as zero width it should solve for U+3164 HANGUL FILLER, or I can add it manually.

I agree about some jamo are meant to be combined, and this library assumes as such, see test case:

wcwidth/tests/test_core.py

Lines 225 to 244 in 056ee4b

	def test_kr_jamo():
	"""
	Test basic combining of HANGUL CHOSEONG and JUNGSEONG
	Example and from Raymond Chen's blog post,
	https://devblogs.microsoft.com/oldnewthing/20201009-00/?p=104351
	"""
	# This is an example where both characters are "wide" when displayed alone.
	#
	# But JUNGSEONG (vowel) is designed for combination with a CHOSEONG (consonant).
	#
	# This wcwidth library understands their width only when combination,
	# and not by independent display, like other zero-width characters that may
	# only combine with an appropriate preceding character.
	phrase = (
	u"\u1100" # ᄀ HANGUL CHOSEONG KIYEOK (consonant)
	u"\u1161" # ᅡ HANGUL JUNGSEONG A (vowel)
	)
	expect_length_each = (2, 0)
	expect_length_phrase = 2