enable non-latin variable descriptions in CodeFileEditor

fix following backtrace:

UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-7: ordinal not in range(128)
Traceback (most recent call last):
File "beremiz/editors/CodeFileEditor.py", line 610, in GetValue
return str(self.data[row].get(self.GetColLabelValue(col, False), ""))
UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-7: ordinal not in range(128)

     1

     2

                  <xsd:element name="Linux">

     3

                    <xsd:complexType>

     4

                      %(toolchain_gcc)s

     5

                    </xsd:complexType>

     6

                  </xsd:element>