p-winds v1.2.2

This new version is an update based on the referee report of the manuscript submitted to Astronomy & Astrophysics.

New in this version (compared to v.1.1):

• hydrogen.py requires a first guess for the mean molecular weight as input, but it can be self-consistently calculated by setting relax_solution to True
• hydrogen.py does not require a value for the average H ion fraction anymore
• parker.sound_speed() now takes as input only temperature and mean molecular weight
• parker has a new function to calculate the average mean molecular weight as in Eq. A.3 in Lampón et al. (2020)
• relax_solution now checks for changes in the entire population profile instead of only the outer layer, both in the hydrogen and helium modules
• Corrected the implementation of turbulence broadening to reflect the same formulation of Lampón et al. (2020)
• Fixed a bug in the exact photoionization calculation
• Corrected a mistake in the calculation of the Guassian broadening term in the Voigt profiles