fix display of ARRAY fields inside of structure data types.

Previously ARRAY fields in structures were displayed, for example,
like 'ARRAY [1..2] OF ARRAY' instead of 'ARRAY [1..2] OF INT'. Because
of this error the array type can be really edited.

<?xml version="1.0" encoding="UTF-8"?>
<BaseParams Name="py_ext_0" IEC_Channel="0"/>