i18n Improvements

[ramiy]

update translation strings related issues.

• Security: escaping translation strings with esc_html__() and esc_attr__().
• Replace <a> links with %s placeholder.
• Merge three similar translation strings into one string, and use placeholders for the links
• Add translators comments to string with placeholders (%s, %1$s and %2$s).

[jtsternberg]

When you want to leave comments for translators, the _x() family of functions should be used. e.g.

esc_html_x( 'Enter a youtube, twitter, or instagram URL. Supports services listed at %s.', '%s is a link to codex.wordpress.org/Embeds', 'cmb2' ),

[ramiy]

@jtsternberg
Actually, you are wrong.

You should never use context _x() function to describe placeholders. You should use only translator comments /* translators: %s: placeholder description */. The translator comment will appear on the sidebar:

As for the _x(), in WordPress core, we use context functions when a string is used in many places, but we want one of those strings to have a different meaning. When we add the context function, this string will appear as a separate string in translate.wordpress.org.

When using context function, It creates a new line in translate.wordpress.org, and allows you to provide a different meaning for this particular string.

[jtsternberg]

Oh wow, well thank you very much for educating me! Looks like I've been using those functions improperly. I'll review this a bit more thoroughly when I get back to my computer, but should be good. Thanks again!

[jazzsequence]

@jtsternberg the best example of proper use of _x would be:

_x( 'Buffalo', 'textdomain', 'A city in New York.' );
_x( 'Buffalo', 'textdomain', 'A large animal that lives in North America' );

[jtsternberg]

Thanks for you contribution @ramiy!