Fix false positive fortran order warning

[hofaflo]

Executing the example code for writing an edf file via the highlevel interface:

import numpy as np
from pyedflib import highlevel

signals = np.random.rand(5, 256*300)*200
channel_names = ['ch1', 'ch2', 'ch3', 'ch4', 'ch5']
signal_headers = highlevel.make_signal_headers(channel_names, sample_frequency=256)
header = highlevel.make_header(patientname='patient_x', gender='Female')
highlevel.write_edf('edf_file.edf', signals, signal_headers, header)

causes the following warning to be issued, even though the array is in C-order:

UserWarning: signals are in Fortran order. Will automatically transfer to C order for compatibility with edflib.

This is because the check for fortran order iterates over all passed arrays, which are then 1d-arrays, so they are always both c_contiguous and f_contiguous.

[skjerns]

Seems like a good addition! Thanks a lot! :)