Remove requirement of data file for SAMPLER and OPTIMIZER
We still use the runOPAL.py scheme with template / data file. However the design variables could be easily looked up in the dictionary or we invent new types: DvarReal etc.
[Edit: this has been moved to a separate issue, see #249 (closed)! If we could define quantities of interest (a la optimizer) and write them to the json file lengthly post processing would be avoided.]