Buffer/Simplification/Poly

Hi,

it would be nice to have the ability to add a buffer to the boundary. Sometimes you simply want to cut .pbf files so adding a buffer of 100-5000m would be nice.

Also when using this a simplification of the result to reduce nodes would be cool.

And while at it. Most tools like osmium/osmconvert use "poly" files to cut pbf - So adding a ".poly" download would be cool.

Flo