Implementing Voigt profiles in fiber tracing

[XimePS]

Implementing Voigt profiles for fiber tracing in fit_profile module:

-Creating a Voigt class for fit the parameters: centroids, amplitudes and FWHMs.
-Creating a Lorentzs class for fit the parameters: centroids, amplitudes and FWHM lorentzian.
-Creating Voigts_width class for fit only the FWHMs.
-Creating Voigts_flux class for fit only the amplitudes.

Implementing fitMultiVoigt in spectrum1d module:

-Adding to class Spectrum1D the fitMultiVoigt method.

Implementing trace_Voigt_fibers in imageMethod module:

-Defining the function to fit with the fiber profiles with the Voigt function.