Finally appeased the compiler. Need to do some real cleaning up on the relationship between canvas and vk processor

src/vkprocessor.rs

@@ -412,7 +412,7 @@ impl<'a> VkProcessor<'a> {
         I can't replace canvas.
         */
 
-        self.canvas.draw_commands(&mut command_buffer, framebuffers, image_num);
+        let mut command_buffer = self.canvas.draw_commands(command_buffer, framebuffers, image_num);
 
         //self.canvas =  mem::replace(&mut self.canvas,