The following test cases:
- 04-JT60SA
- 05-JT60SA-startup
- 06-ITER-startup.Mixed
were affected by the bug fixed in f82f91bc, so their reference outputs
had to be updated.
1. Introduces enumerations (and some booleans) intended to replace all
the magic numbers used throughout the code to represent multiple
choices.
2. Replace the gray_params.sh script a new one that automatically
generates code for all the GRAY parameters by parsing
gray_params.f90.
3. Also generate extra code to accept the enum identifiers as valid
values in the configuration files and command line arguments.
4. Set sensible default values for parameters that are rarely changes.
