display/text: Add layer support

virtual-programs/display/text.folk

@@ -208,6 +208,7 @@ On process "display" {
         set anchor [dict_getdef $options anchor "center"]
         set radians [dict_getdef $options radians 0]
         set color [getColor [dict_getdef $options color white]]
+        set layer [dict_getdef $options layer 0]
 
         if {$anchor == "topleft"} {
             set anchor [list 0 0]
@@ -238,6 +239,6 @@ On process "display" {
 
         # We need to batch into one wish so we don't deal with n^2
         # checks for existing statements for n glyphs.
-        Wish the GPU draws pipeline "glyph" with instances $instances
+        Wish the GPU draws pipeline "glyph" with instances $instances layer $layer
     }
 }