fixes to initial_condition_decomposition

testing a bit initial_condition_decomposition I noted the following small bugs to preprocessor:

• options graph_format and nodisplay should trigger the associated field in options_.initial_condition_decomposition and not in options_
• option fig_name should trigger the associated field in options_.initial_condition_decomposition and not in options_.plot_shock_decomposition

I am finishing in the meantime all provisions (see dynare!1677 (merged))