Kill jsts

[tcql]

This PR uses the greiner-hormann algorithm that I've been working on implementing. It's considerably faster than JSTS, and removes our dependency on JSTS, aside from turf-buffer.

There are likely some quirks / edge case failures here, but we'll deal with those as they come up. Here's some known differences in the behavior:

• Intersect / Union / Difference no longer will return linestrings or points for cases where polygons touch at only an edge or a point (or several edges or points)
• Returned point orders may be different

[jaketangosierra]

+1 on this, JSTS dependency is weird in react-native, and I'd love to use turfjs there.

[tcql]

Turfjs/turf-intersect#10 (comment)