Merge drawtowerentities() into drawentities()

This removes lots of duplicated code that drawtowerentities() did,
because all that really changed was accounting for map.ypos (which can
be done conditionally) and where and when the room wrapped (which can
also be done conditionally).

desktop_version/src/Render.cpp

@@ -2592,7 +2592,7 @@ void towerrender()
         }
     }
 
-    graphics.drawtowerentities();
+    graphics.drawentities();
 
     graphics.drawtowerspikes();