fix: modify the output style of list type fields to enable auto parse

To enable auto parse of Yaml format, the output style of fields with one more elements was reorganized.

io/writeYaml.m

@@ -9,6 +9,7 @@ function writeYaml(model,name)
 %
 %   Benjamin Sanchez, 2018-04-11
 %   Simonas Marcisauskas, 2018-04-13
+%   Hao Wang, 2018-05-14
 %
 
 %Check that model is in RAVEN format:
@@ -191,9 +192,7 @@ function writeField(model,fid,fieldName,type,pos,name)
             list = strrep(field{pos},' ','');     %Exception for eccodes
             list = strsplit(list,';');
         end
-        if length(list) == 1 && ~strcmp(list{1},'')
-            fprintf(fid,['    ' name ': ' list{1} '\n']);
-        elseif length(list) > 1
+        if ~strcmp(list{1},'')
             fprintf(fid,['    ' name ':\n']);
             for i = 1:length(list)
                 fprintf(fid,['        - ' list{i} '\n']);