Allow passing array of hook names to add_filter and add_action

[joehoyle]

One thing I wish I was able to do is pass multiple hooks to add_action() and add_filter(), so I could do stuff like this:

add_action( ["admin_print_styles-post.php", "admin_print_styles-post-new.php"], function() {
    echo 'Two in one!';
} );

Currently If you want to use a closure you have to do something like

add_action( "admin_print_styles-post.php", $hook = function() {
    echo 'Two in one!';
} );
add_action( "admin_print_styles-post-new.php", $hook );

[scribu]

#14280