Suggestion: add \extrafloats to common

[ajrouvoet]

Because the margin is used extensively, latex is more prone to reporting 'too many unprocessed float errors' when using tufte-latex. I've struggled with fixing that for a while, but found that the following simple solution does the job:

\extrafloats{100}

Would it make sense to add this to the commons? If not, at least a solution is now documented here :)