Returns a list of valid taxes for a certain chart.
If the optional param transdate exists one entry in the returning list
-may get the attribute C<is_default> for this specific tax-dependant date.
+may get the attribute C<is_default> for this specific tax-dependent date.
The possible entries are filtered by the charttype of the tax, i.e. only taxes
whose chart_categories match the category of the chart will be shown.