Replace test_wrapper() in test_altai.py

[ekaterinailin]

What needs to be created or improved?

Replace test_wrapper() in test_altai.py with tests that do the same on the different parts of the refurbished wrapper() function, once it takes FlareLightCurve objects instead of numpy.recarrays.

Can you provide an example?

from ..flarelc import FlareLightCurve

def test_wrapper():
    lc = FlareLightCurve(EPIC)
    assert lc == 'something'
    lc = lc.detrend()
    assert lc == [...]

What is the goal / expected behaviour?

Run a full integration test to make sure we can push a light curve through the pipeline from A to Z.

[ekaterinailin]

This one was split into different methods of FlareLightCurve, which are tested individually.