Allow floats or integers in 'transfer_func' directly
Instead of:
&Data_arrays
transfer_func(1) = "p1 + p2 * x1"
from_data_arrays(1) = "x1"
from_parameter_values = "1.2", "-0.5"
allow
&Data_arrays
transfer_func(1) = "1.2 - 0.5 * x1"
from_data_arrays(1) = "x1"