handle root case better

rewrite and fix remove

fix removal: creating broken trees that later lead to removal of wron…

…g points

fix removal: creating broken trees that later lead to removal of wron…

…g points

style: cleanup tests

Merge pull request paulmach#75 from paulmach/knearest-sort

quadtree: sort KNearest results closest first

Merge pull request paulmach#66 from si3nloong/master

📦️ chore: bump dependencies

encoding/mvt: remove github.com/pkg/errors as a dependency

geojson: don't error on nil geometry

okay as per the spec https://tools.ietf.org/html/rfc7946#section-3.2

update gogo/protobuf and pkg/errors dependencies