fix #7845 new genus or species: setting value of genus or spec. epithet only if the name is not yet known
fix #7831 excluding the current name from the WeaklyRelatedEntityCombobox for genus name and specific epithet
ref #7783 using WeaklyRelatedEntityCombobox in TaxonNameEditor: add, edit buttons working and enabled state updating ok
ref #7783 implementing WeaklyRelatedEntityCombobox according PagingProvider