Few fit examples are broken

1. Mask API was removed from simulation and should be called as simulation.detector().<mask_func>:

fit/scatter2d/fit_with_masks.py:    simulation.maskAll()
fit/scatter2d/fit_along_slices.py:    simulation.maskAll()

fit/scatter2d/fit_with_masks.py:    simulation.addMask(ba.Ellipse(0, 1*deg, 0.5*deg, 0.5*deg), False)
fit/scatter2d/fit_with_masks.py:    simulation.addMask(ba.Ellipse(0.11*deg, 1.25*deg, 0.05*deg, 0.05*deg),
fit/scatter2d/fit_with_masks.py:    simulation.addMask(ba.Polygon(points), True)
fit/scatter2d/fit_with_masks.py:    simulation.addMask(
fit/scatter2d/fit_with_masks.py:    simulation.addMask(
fit/scatter2d/fit_with_masks.py:    simulation.addMask(

fit/scatter2d/fit_along_slices.py:    simulation.addMask(ba.HorizontalLine(alpha_slice_value*deg), False)
fit/scatter2d/fit_along_slices.py:    simulation.addMask(ba.VerticalLine(phi_slice_value*deg), False)

fit/scatter2d/expfit_galaxi.py:    simulation.addMask(ba.Rectangle(101.9, 82.1, 103.7, 85.2), True)
fit/scatter2d/expfit_galaxi.py:    simulation.setRegionOfInterest(85, 70, 120, 92.)

2. expfit_galaxi.py: R3 is not imported. Probably somewhere else.

3. expfit_galaxi.py and few other examples (UPD: fixed):

File ~/Projects/bornagain/build/lib/bornagain/ba_plot.py:409 in plot_simres
    axes_limits = get_axes_limits(result, units)

  File ~/Projects/bornagain/build/lib/bornagain/ba_plot.py:122 in get_axes_limits
    for i in range(result.rank()):

AttributeError: 'tuple' object has no attribute 'rank'