TypeError in phoenix_precision with only 3 args.

[jason-neal]

Describe the bug
TypeError in phoenix_precision with only 3 args.

To Reproduce
Steps to reproduce the behavior:

 phoenix_precision.py -m 2800 -l 4.5 -m 0.0
Traceback (most recent call last):
  File "/home/jneal/anaconda3/envs/eniric/bin/phoenix_precision.py", line 7, in                     <module>
    exec(compile(f.read(), __file__, 'exec'))
  File "/home/jneal/Phd/Codes/eniric/scripts/phoenix_precision.py", line 455, in                     <module>
    models_list = itertools.product(args.temp, args.logg, args.metal, args.alpha                    )
TypeError: 'NoneType' object is not iterable

[jason-neal]

This command was broken in that it has -m flag twice and no -t flag. The type error has been resolved using default temperature of 3900 K.

The last -m overwrote the first incorrect one.