remove_accents() improvements for Chinese pinyin permalinks

[bolo1988]

echo str_replace(' ', '-', str_replace('.', '', sanitize_file_name(remove_accents(strtolower('Lǚcì')))));

the result:

lǚcì

and i found remove_accents() can't convert the following chars:
ǎ -> a
ǒ -> o
ǚ -> v/u
ǐ -> i
ǔ -> u

[bolo1988]

Replying to bolo1988:

echo str_replace(' ', '-', str_replace('.', '', sanitize_file_name(remove_accents(strtolower('Lǚcì')))));

the result:

lǚcì

and i found remove_accents() can't convert the following chars:
ǎ -> a,
ǒ -> o,
ǚ -> v/u,
ǐ -> i,
ǔ -> u

[bolo1988]

		$pinyin_in = array(
			chr(199).chr(142) => 'a',
			chr(199).chr(144) => 'i',
			chr(199).chr(146) => 'o',
			chr(199).chr(148) => 'u',
			chr(199).chr(154) => 'u',
		);
		$output = str_replace(array_keys($pinyin_in), $pinyin_in, $string);

This code can fixed the problem

[SergeyBiryukov]

20772.patch​ adds the missing ​Pinyin diacritics to the replacement list.

Unit tests: ​[UT724]

[nacin]

In [21859]:

Add Pinyin diacritics to remove_accents(). Remove these diacritics in sanitize_title_with_dashes() on save as well. props bolo1988, SergeyBiryukov. fixes #20772.