Fix overlay conversions

We don't want to do any colorspace conversion in the overlayed image.

Thus we
- include colorin module in the "module filter out" list
- we don't enforce colorin via it's commit_params if we develop with finalscale enabled.

src/iop/colorin.c

@@ -1351,7 +1351,8 @@ void commit_params(struct dt_iop_module_t *self,
     piece->enabled = FALSE;
     return;
   }
-  piece->enabled = TRUE;
+  if(!(piece->pipe->type & DT_DEV_PIXELPIPE_IMAGE_FINAL))
+    piece->enabled = TRUE;
 
   if(type == DT_COLORSPACE_ENHANCED_MATRIX)
   {

src/iop/overlay.c

@@ -189,7 +189,6 @@ static GList *_get_disabled_modules(const dt_iop_module_t *self,
      There are some exceptions:
        - gamma and finalscale are required
        - crop and &ashift make sense
-       - colorin is good to keep too
      The list order does not matter
   */
 
@@ -207,7 +206,6 @@ static GList *_get_disabled_modules(const dt_iop_module_t *self,
           && !dt_iop_module_is(mod->so, "gamma")
           && !dt_iop_module_is(mod->so, "finalscale")
           && !dt_iop_module_is(mod->so, "crop")
-          && !dt_iop_module_is(mod->so, "colorin")
           && !dt_iop_module_is(mod->so, "ashift"))
     || (is_current
          && ( dt_iop_module_is(mod->so, "overlay")