fix error if non-latin character was entered in initial value in
data type element

Traceback (most recent call last):
File "/home/beremiz/editors/DataTypeEditor.py", line 575, in OnStructureElementsGridCellChange
value = self.StructureElementsTable.GetValue(row, col)
File "/home/beremiz/editors/DataTypeEditor.py", line 80, in GetValue
return str(value)
UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-2: ordinal not in range(128)
Traceback (most recent call last):
File "/home/beremiz/editors/DataTypeEditor.py", line 80, in GetValue
return str(value)
UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-2: ordinal not in range(128)
Traceback (most recent call last):
File "/home/beremiz/editors/DataTypeEditor.py", line 80, in GetValue
return str(value)
UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-2: ordinal not in range(128)

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          <xsd:attribute name="Command" type="xsd:string" use="optional" default="make -C %(buildpath)s all BEREMIZSRC=%(src)s BEREMIZCFLAGS=%(cflags)s MD5=%(md5)s USE_BEREMIZ=1 FROM_BEREMIZ=1"/>

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