Integrate Peter Gao's Code about virga

[natashabatalha]

@logan-pearce is going to help integrate this

[natashabatalha]

Tholin:

      pvap_tholin_bars = 10**(7.6106 - 11382./T) !this is actually the KCl vapor pressure, not a real tholin one. 
c     Then convert from bars to dynes/cm^2    
      pvap_tholin = pvap_tholin_bars*1e6 

Soot:

      pvap_soot_bars = 10.d0**(7.6106 - 11382./t) !this is actually the KCl vapor pressure, not a real soot one. 
c     Then convert from bars to dynes/cm^2    
      pvap_soot = pvap_soot_bars*1e6   

Gas Properties from @semoran

def tholin(mw_atmos, mh = 1,gas_mmr=None):
    """Defines properties for Haze with Khare 1984 tholin refractive indices as if it were solid in atmosphere.
    Parameters
    ----------
    mw_atmos : float
        Mean molecular weight of the atmosphere amu
    gas_mmr : float , optional
        Gas mass mixing ratio
        None points to the default value of : 8.80e-7
    mh : float , optional
        Metallicity, Default is 1=1xSolar
    Returns
    -------
    Mean molecular weight of gas,
    Gas mass mixing ratio
    Density of gas cgs
    """
    if mh != 1: raise Exception("Alert: No M/H Dependence in FakeHaze Routine. Consult your local theorist to determine next steps.")
    if isinstance(gas_mmr, type(None)):
        gas_mmr = 1e-7
    gas_mw = 500. #this actually quite low but for testing.
    gas_mmr = gas_mmr * (gas_mw/mw_atmos)
    rho_p =  1.38 #average in g/cm3 from He+2017 --- can't find Khare report, so we use this for now
    return gas_mw, gas_mmr, rho_p