Displays an error message when the model contains pound expressions and 'bytecode' or 'block' options are present

generates <fname>_steadystate2.m returning parameters as well in case
they have been modified by the user. Added several test cases.

identification; added an example; still necessary to add error message
when restrictions are invalid

dynare_solve.m calls str2func on the function name, so it crashes if it is
passed a function handle. It needs to be passed a string.

In order to avoid warnings in 'nodisplay' mode.

The recursive equations are merged in a recursive block only if they are all backward looking or all forward looking but not both