Enable output option when no computing command is requested and add first option

Closes #121 (closed) and #100 (closed)

merged

mentioned in commit 5c756434

@JohannesPfeifer Thanks, please do not forget to document the first option in the reference manual.

Done in dynare!2361 (merged)

I see that you marked #111 (closed) as fixed in the list of known bugs. This implies that it should be fixed for the 6.x branch. As such I cannot backport your commit since it also adds a new feature (output=first). Could you open a MR fixing only #111 (closed)?