SOLTIGUA SolarCollector and Absorber added
next improvements:
- defocusing signal as an explicit Input/Output (for system control)
- Dynamic Wall (Dext and Dint not available now, they will be required to Solitgua)
- SolarAbsorber with enumeration (for automatic choise of PTMx-18, 24 , 30 ecc ecc)
- IAM as a function of Theta (with enumeration for differents models)

Should we add a SolarField component, which manage at an higher level the field layout configuration (n of tubes, parallel, series, ecc ecc)?
Os shoud it be done simple inside the SolarCollector

BUGS: Still some problems when DNI=0. probably due to the efficiency definition, where the DNI is at the denominator.