Morecantile

* add `parent`, `children`, `neighbors`, `minmax`, `is_valid` methods (https://github.com/developmentseed/morecantile/pull/82)

**breaking changes**

* update `WebMercatorQuad` TMS to match `mercantile` and `GDAL` definition of the half-earth value

* truncate geographic Lon/Lat inputs to the TMS geographic bbox instead of `-180., -90., 180., 90.` (https://github.com/developmentseed/morecantile/pull/79)
* remove `utils.truncate_lnglat` function (https://github.com/developmentseed/morecantile/pull/79)

* Allow zoom_for_res to work for a TMS with a minzoom > 0 (author samn, https://github.com/developmentseed/morecantile/pull/78)

* add `WGS1984Quad` (`WGS84/epgs:4326`) TileMatrixSet (https://github.com/developmentseed/morecantile/pull/74)

* add `_geographic_crs` definition in `__init__` to make sure it's initialized from user input (author davenquinn, https://github.com/developmentseed/morecantile/pull/72)

* rename `_to_wgs84` and `_from_wgs84` private attributes to `_to_geographic` and `_from_geographic` (https://github.com/developmentseed/morecantile/pull/68)
* add `_geographic_crs` private attribute to `morecantile.TileMatrixSet` to define the CRS used in `_to_geographic` and `_from_geographic` (https://github.com/developmentseed/morecantile/pull/68)
* fix `TileMatrixSet._invert_axis` method to only check axis information (https://github.com/developmentseed/morecantile/pull/71)