Save chest label when exiting formspec

When using the form to edit a chest label, apply the edited label whenever the
form is submitted with the text field included, rather than only if the form's
specific "finished editing" button is used.  This supports the natural use of
<ret> to indicate that text editing is complete, which works with other text
editing forms such as that for signs.

technic_chests/register.lua

@@ -69,7 +69,7 @@ local function get_receive_fields(name, data)
 		if fields.edit_infotext then
 			page = "edit_infotext"
 		end
-		if fields.save_infotext then
+		if fields.infotext_box then
 			meta:set_string("infotext", fields.infotext_box)
 		end
 		local formspec = data.formspec