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.
original tax always appears in the dropdown.
The functions returns an array which may be used for building dropdowns in ar/ap/gl code.
+
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=head1 TODO