Changes in restrict and in_interval

[gviejo]

Hello
The first change is the same as the issue I opened.
The second change is because in restrict, .iloc doesn't accept anything else than an int.
For exemple if I have a TsdFrame such as:

frame = nts.TsdFrame(t = times, d = data, columns = ['angle', 'xpos', 'ypos'])

and I cut it to take only the angle:

angle = frame['angle']

and try to restrict it:

angle.restrict(epoch)

in restrict:

s = tsd_r.iloc[:, col]

will bug because col is 'angle' and not 0.
Since Tsd is a one dimensional dataset, it can be assumed it's always the first column.

Best

Guillaume