GenBank format: be able to handle locations in a remote entry

According to the GenBank format specification, locations of features may be specified for remote entries, e.g.:

gene complement(AC021573.10:35878..97652)

Here "AC021573.10" is the name of another GenBank entry.

UGENE does not currently support it completely and, therefore, it can't handle correctly some GenBank files (see UGENE-5160).