String variable with whitespaces are incorrectly parsed

[rlacroix]

How to reproduce:

   <file_definition type="multiple_file" par_access="collective" output_freq="6h" output_level="10" enabled=".TRUE.">
     <file id="output" name="output"> 
        <field field_ref="field_A" />
        <variable id="my_attribute1" type="string">surf_att</variable>
        <variable id="my_attribute2" type="string">I love whitespaces</variable>
     </file>
   </file_definition>

Using this configuration file will result in the following NetCDF output:

// global attributes:
		:name = "output" ;
		:description = "Created by xios" ;
                ...
		:my_attribute1 = "surf_att" ;
		:my_attribute2 = "I" ;

Expected result would be :my_attribute2 = "I love whitespaces" ;

[rlacroix]

Fixed by r530.