Read access to icon_selector on a LuaGuiElement

[Osmo]

I'm working on a mod that allows editing Gui Elements in-game, and all of the properties which can be set on the elements can then be read back in some way.
Except for the icon_selector, which can be set on textboxes and textfields, but there is no way for a script to read whether it is set.
Read-write access would be good if possible, but just read only is more than enough.

[Bilka]

Okay, added LuaGuiElement::icon_selector read for 2.0.67.