Fix curly quotes around numbers when applicable.

Adds unit tests.

Props filosofo, mrmist, aliso, MikeHansenMe, miqrogroove.
Fixes #8775.


git-svn-id: https://develop.svn.wordpress.org/trunk@28721 602fd350-edb4-49c9-b593-d223f7449a82
Set a variable for like-escaped string before looping in `WP_User_Query::get_search_sql()`. 

Props miqrogroove.
Fixes #10041.


git-svn-id: https://develop.svn.wordpress.org/trunk@28722 602fd350-edb4-49c9-b593-d223f7449a82