4e4fc2ffdb9043487ac031b2c4dac630a392a58c Use load_xls_file_data in read_variables (for consistency with CSV)

================================ DYNARE MAKE CHECK MATLAB RESULTS ================================ | TOTAL: 214 | PASS: 213 | FAIL: 0 | XFAIL: 1 | XPASS: 0

================================ DYNARE MAKE CHECK OCTAVE RESULTS ================================ | TOTAL: 211 | PASS: 210 | FAIL: 0 | XFAIL: 1 | XPASS: 0

A full log can be found on karaba in '/tmp/dynare-master-check-Q0D7X2KdnY.log'.