Move text box fadeout removal to Graphics::drawgui()

Something that's slightly annoying is that in order to make the vector
of text boxes be properly used, the text box cannot remove itself.
Because the text box does not know it's in a vector. So move the removal
of the text box to drawgui() instead.

desktop_version/src/Graphics.cpp

@@ -586,6 +586,11 @@ void Graphics::drawgui()
         textbox[i].update();
         if (textbox[i].active)
         {
+            if (textbox[i].tm == 2 && textbox[i].tl <= 0.5)
+            {
+                textbox[i].active = false;
+            }
+
             if (textbox[i].r == 0 && textbox[i].g == 0 && textbox[i].b == 0)
             {
                 if(flipmode)

desktop_version/src/Textbox.cpp

@@ -105,7 +105,7 @@ void textboxclass::update()
         if (tl <= 0.5)
         {
             tl = 0.5;
-            active = false;
+            //this textbox will be removed by drawgui() later
         }
         setcol(int(tr * tl), int(tg * tl), int(tb * tl));
     }