Link function problems

[lindeloev]

• [ ] fit$simulate(fit, data, ...) apparently doesn't respect the link function in the family? Try e.g. simulating from mcp_example("demo") with another link function.
• [ ] Try mcp_example("demo") with family = gaussian("log") and see that it doesn't fit the last segment appropriately.
• [ ] Think about whether "sim" and "ok" cols of summary() should transform if data was simulated using another link function (probably not).