Change the default processing profile

[erikmannerfelt]

The current default processing profile has these filters:

zero_corr_max_peak
equidistant_traces
correct_antenna_separation
normalize_horizontal_magnitudes(0.3)
unphase
kirchhoff_migration2d
normalize_horizontal_magnitudes(0.3)
dewow(5)
auto_gain(100)

There are two issues in this profile:

• unphase is not common and may even be faulty, as there's no good theoretical basis for its functionality.
• kirchhoff_migration2d is very useful for deep stuff like glacier thickness, but may not be as useful for high-frequency radar like snow stratigraphy. Therefore, this should be optional (say in another profile or just be excluded completely)

As the types of profiles start to widen, perhaps it could be useful with a --profile=PROFILE argument that would allow for many different types of profiles. It could even be combined with the suggestion of #9 where --profile=steps.txt is the way to use an external step file!