influence of error in sailsheet setting added to simulator

[danhaus]

no physics included, just linear proportionality

[takluyver]

I think we should avoid committing the .DS_Store files. We can add that name to .gitignore to avoid it in the future, but we'll need to remove the ones that were added here.

[Nanoseb]

@takluyver should be ok now @danhaus thanks for this! going to merge now