Select io

At run time, allow the user to specify the output fields through parameters in the YAML file. Adds the option -o FILENAME to generate a list of possible fields.

Implements #410 (closed).

examples/SedovBlast_3D/sedov.yml

@@ -19,7 +19,7 @@ Snapshots:
   time_first:          0.    # Time of the first output (in internal units)
   delta_time:          1e-2  # Time difference between consecutive outputs (in internal units)
   compression:         4
-  
+ 
 # Parameters governing the conserved quantities statistics
 Statistics:
   delta_time:          1e-3 # Time between statistics output
@@ -33,4 +33,4 @@ SPH:
 InitialConditions:
   file_name:                    ./sedov.hdf5          
   smoothing_length_scaling:     3.33
-
+ 
\ No newline at end of file