Read FMU input variable start values from model description

[ewidl]

In the current version (v0.0.4), initial start values for FMU variables are only read from the client config. For client inputs, the corresponding start values should be read from the FMU model description (if available) and applied as default.

NOTE: This will require changes in FMI++, because the model description definition and the function call to retrieve it from an FMU is ignored by SWIG!