I18N: Allow the length of automatically generated excerpts to be localized.

This introduces three new strings that can be used to control the maximum length of automatically generated excerpts for posts, comments, and draft post previews in the dashboard. Optionally combined with the existing word count type control this allows languages which include many multibyte characters to specify more appropriate maximum excerpt lengths.

Props miyauchi, birgire, johnbillion

Fixes #44541


git-svn-id: https://develop.svn.wordpress.org/trunk@45505 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/data/languages/ja_JP.po

@@ -40,3 +40,30 @@ msgstr "number_format_thousands_sep"
 #: wp-includes/script-loader.php:620
 msgid "Update %s now"
 msgstr "今すぐ %s を更新"
+
+#. translators: If your word count is based on single characters (e.g. East
+#. Asian characters), enter 'characters_excluding_spaces' or
+#. 'characters_including_spaces'. Otherwise, enter 'words'. Do not translate
+#. into your own language.
+#: wp-includes/formatting.php:3372 wp-includes/script-loader.php:1100
+msgctxt "Word count type. Do not translate!"
+msgid "words"
+msgstr "characters_including_spaces"
+
+#. translators: Maximum number of words used in a post excerpt.
+#: wp-includes/formatting.php:3640
+msgctxt "excerpt_length"
+msgid "55"
+msgstr "110"
+
+#. translators: Maximum number of words used in a comment excerpt.
+#: wp-includes/comment-template.ph:599
+msgctxt "comment_excerpt_length"
+msgid "20"
+msgstr "40"
+
+#. translators: Maximum number of words used in a preview of a draft on the dashboard.
+#: wp-admin/includes/dashboard.php:591
+msgctxt "draft_length"
+msgid "10"
+msgstr "40"