Allow screen_icon() to return not echo

[aaroncampbell]

I'd like to see screen_icon() be able to return it's value rather than just echo it. I'm willing to patch it, but are we trying to stick to the get_*() functions, or do we want another parameter?

[nacin]

get_* would be nice.

[aaroncampbell]

The patch adds get_screen_icon() and uses it in screen_icon(). The only change is to use esc_attr on $name which is used as part of the div id.

[aaroncampbell]

Patch for the current trunk.

[westi]

Why not just build a string rather than use sprintf?

[aaroncampbell]

Good point. New patch without sprintf

[ryan]

(In [17656]) Introduce get_screen_icon(). Props aaroncampbell. fixes #15377