Some relaxed introspection tests

Float module parameters can be outside the desired range due to rounding errors when calculating
values from bauhaus sliders.
We introduce an eps here in the introspection checks and backreport if that check was required to
flag all_ok.

While being here
- some improved logs
- corrected a misleading control_log message
- as dt_masks_group_get_hash_buffer_length(grp) could possibly be pretty large we do a safety check
  while allocating.

src/develop/imageop.c

@@ -1993,14 +1993,24 @@ gboolean _iop_validate_params(dt_introspection_field_t *field,
     break;
   case DT_INTROSPECTION_TYPE_FLOAT:
     all_ok = dt_isnan(*(float*)p)
-      || dt_isinf(*(float*)p)
-      || (*(float*)p == field->Float.Default)
-      || (*(float*)p >= field->Float.Min && *(float*)p <= field->Float.Max);
+          || dt_isinf(*(float*)p)
+          || (*(float*)p >= field->Float.Min && *(float*)p <= field->Float.Max);
+    gboolean relaxed = FALSE;
+    if(!all_ok)
+    {
+      const float eps = 1.00001f;
+      if(*(float*)p >= field->Float.Min / eps && *(float*)p <= field->Float.Max * eps)
+      {
+        all_ok = TRUE;
+        relaxed = TRUE;
+      }
+    }
     values = g_strdup_printf
-      (" (%f - [%f..%f] : default %f)",
+      (" (%.8f - [%f..%f] : default %f)%s",
        *(float*)p,
        field->Float.Min, field->Float.Max,
-       field->Float.Default);
+       field->Float.Default,
+       relaxed ? " relaxed range" : "");
     break;
   case DT_INTROSPECTION_TYPE_INT:
     all_ok = (*(int*)p >= field->Int.Min && *(int*)p <= field->Int.Max);
@@ -2085,7 +2095,7 @@ gboolean _iop_validate_params(dt_introspection_field_t *field,
   if(all_ok)
   {
     dt_print(DT_DEBUG_ALWAYS,
-             "[iop_validate_params] `%s' data for type \"%s\"%s%s%s\n",
+             "[iop_validate_params] `%s' validated data for type \"%s\"%s%s%s\n",
              name, field->header.type_name,
              *field->header.name ? ", field: " : "",
              field->header.name, values ? values : "");
@@ -2139,9 +2149,9 @@ void dt_iop_commit_params(dt_iop_module_t *module,
                              module->so->op))
     {
       // FIXME maybe we can hint a warning in the module UI or possibly
-      // disable the piece ?
+      // disable the piece ? Requires more introspection fixes (especially enums) to be safe
       dt_control_log
-        (_("'%s' has been disabled because of an introspection error"), module->op);
+        (_("'%s' has an introspection error"), module->op);
     }
   }
 
@@ -2171,9 +2181,12 @@ void dt_iop_commit_params(dt_iop_module_t *module,
       {
         const size_t mlen = dt_masks_group_get_hash_buffer_length(grp);
         char *str = malloc(mlen);
-        dt_masks_group_get_hash_buffer(grp, str);
-        phash = dt_hash(phash, str, mlen);
-        free(str);
+        if(str)
+        {
+          dt_masks_group_get_hash_buffer(grp, str);
+          phash = dt_hash(phash, str, mlen);
+          free(str);
+        }
       }
 
       if(blendop_params->mask_mode & DEVELOP_MASK_RASTER && new_raster)