[FEA] Modify the way sfdiffsim receives layers velocity input

[Dirack]

🎉 Feature request

Is your feature request related to a problem? Please describe.

Now, program sfdiffsim is receiving a velocity sample for each hyperbola that will be generated in the stacked section.
Modify that behavior of the program to a new one, to receive the layers velocity as input that is assigned to a set of hyperbolas that corresponds to the same reflector.

Describe the solution you'd like

Receiving the velocity for a given set of hyperbolas allow to simulate the hyperbolas for each reflector in a loop.
For instance:

# Loop over reflectors
numberOfReflectors = len(layers)
section = 'stackedSection'

for i in range(numberOfReflectors):

	.
        .
        .

	# Diffraction simulation in stacked section
	Flow([returnedSection,diffSection],[section,t0sFile,m0sFile],
		'''
		diffsim diff=${TARGETS[1]} aperture=1
		t0=${SOURCES[1]} m0=${SOURCES[2]} v=%g freq=10 verb=y
		''' % (velocities[i]))

	section = returnedSection

Program sfdiffsim generates a set of hyperbolas for a given velocity in each iteration of the loop and stores it in a
'diffSection' file. The RSF files 'diffSection' is the simulated diffraction hyperbolas only and 'returnedSection'
is the summation of simulated diffractions plus stacked section given as input.

Describe alternatives you've considered

The picking of (m0,t0) pairs in the stacked section can be done using iterative picking with sfipick program available in Madagascar package.