Do not evaluate explicitly ICs

Currently initial conditions (ICs) are evaluated at the beginning of TFmain. This prohibits to sample also ICs by defining them as a function of parameters in one of the IQMmodel formats.

Looks like x0 from evalModelOptions and evalModel, x0 is not used at all and can be safely removed; when no ICs are passed explicitly to IQMPsimulate (use [] instead), the ICs will be correctly implicitly read and evaluated if required.