3.0.0

* [x] Add 2014 boundaries
* [x] Add PLZ boundaries
* [x] Remove internal lake boundaries using `topojson-merge`
* [x] Replace `bin/topomergeids` with `topojson-group`
* [x] Scale projected topology only *after* combining layers (see #7)
* [ ] Add per-canton combination of municipalities and lakes (e.g. `zh-municipalities-lakes.json`)
* [ ] Add tests