biparabolic airfoil not in regression tests

[bigfooted]

Is your feature request related to a problem? Please describe.
The biparabolic airfoil in Testcases/euler/biparabolic
is not in a regression test. What is needed:

1. update the config file
2. test with current develop version
3. optimize settings for best convergence
4. add to regression test

[Syphonicc]

Hi, I'd like to take this one I'm new to SU2 but comfortable running Euler airfoil cases. Happy to work through the four steps.

[bigfooted]

Sounds good, just go ahead and add it to either serial_regression.py or parallel_regression.py as a regression test