[bug] Custom reactant enthalpy is overwritten

[markleader]

Summary
Excerpt from external email: "I think it will be much appreciated by all users if on top of the fuel/oxidizers from the database one could add reactant species (htpb for example) by specifying atomic composition and enthalpy of formation of the reactant.

Also when I try to impose enthalpy of formation of existing species (for example changing the enthalpy of formation of butadiene), it is overwritten in the execution of the program."

Reproduction

• Interface: legacy
• Minimal input / steps (attach .inp if relevant):
• Command or API call used:

Expected behavior
What you expected to happen.

Actual behavior
What happened (include key error messages/output).

Environment

• OS:
• CEA version/commit:
• Compiler or Python version (if relevant):

Additional context

prob case = my_test________4458 ro equilibrium
  
 # Pressure (1 value):
 p,atm= 80
 # Supersonic Area Ratio (1 value):
 supar= 8.35
  
 # You selected the following reactants:
 reac
 name AL(cr)            wt%= 18.0000  t,k= 298.000
 name C4H6,butadiene    wt%= 13.0000  t,k= 298.000 rho,g/cc=   0.900 h,kj/mole=-1
 50.000
 name NH4CLO4(I)        wt%= 69.0000  t,k= 298.000