Cosmetic Changes to Graphs
Make UnivariateSpectralDensity save plots to graphs-folder

Also make the plots obey the nodisplay option
Make error message for prior violation more explicit by adding second argument to info()
Fix bug where initial_estimation_checks was performed on prior mean instead of specified mode

If the mode_file option was used, xparam1 was reloaded from the
mode-file after the initial checks, sometimes leading to very cryptic
errors. Now the initial checks already load the correct parameter
vector.
Suppress output of row_header_width
Provide stability mapping with more expressive figure titles
Make sure GSA only computes statistics on original endogenous variables, not auxiliary ones
Provide Redform Mapping with more expressive figure titles
Provide RMSE with more expressive figure titles