Add stdbscan

[ACalleros]

I have been a heavy user of stbscan for the last year. I found the sourcecode on this repo. I am wondering if it can be added to the dbscan library.

[mhahsler]

Hi,

This specific application to spatial-temporal data should be its own package. I will keep it as a feature request. Hopefully, someone will pick it up and create a package.

-Michael