ui/draw: rename ImageOp.Img to Src

To match widget.Image.Src field name.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

ui/app/internal/gpu/gpu.go

@@ -699,7 +699,7 @@ loop:
 		case ops.TypeImage:
 			var op gdraw.ImageOp
 			op.Decode(encOp.Data, encOp.Refs)
-			state.img = op.Img
+			state.img = op.Src
 			state.imgRect = op.Rect
 		case ops.TypeDraw:
 			var op gdraw.DrawOp