Restore behavior of 'nolog' option

The option had been broken by 0e77815e.

This option cannot be entirely handled at the preprocessor level, since the
main log file is created at the MATLAB/Octave level. Handle it via a dedicated
regular expression.

matlab/dynare.m

@@ -259,6 +259,12 @@ no_log = 0;
 for i=1:length(varargin)
     no_log = no_log || strcmp(varargin{i}, 'nolog');
 end
+fid = fopen(fname, 'r');
+firstline = fgetl(fid);
+fclose(fid);
+if ~isempty(regexp(firstline, '//\s*--\+\s*options:(|.*\s|.*,)nolog(|\s.*|,.*)\+--'))
+    no_log = 1;
+end
 if ~no_log
     logname = [fname(1:end-4) '.log'];
     fid = fopen(logname, 'w');