The attached patch adds a 'drupalFID' member to each feature passed to OpenLayers.
This is needed to distinguish actual features (elments of the 'features' array passed
as second argument to Drupal.openlayers.addFeatures) after they are exploded into
components in the case of GEOMETRYCOLLECTION types.
The association will be useful to do things like avoiding duplicated informations in popup/tooltips
and properly count distinct features in case of clustering (for say, dynamic styling based on number of
actual features composing a cluster).
See also #805264 for some context.