Factor out primitives and types to GeometryOpsCore.jl (#220)

* Factor all core stuff out into a GeometryOpsCore package

This basically guts the `types.jl` and `primitives.jl` files from GeometryOps and puts them into a new, low-dependency module that other packages can utilize for a convenient structure.

* Define `Manifold` and subtypes Linear, Spherical, Geodesic

The name `Manifold` is up for debate, I just wanted some supertype for dispatch constraints.

* Fix integration issues, get things working

* Fix import error

* Finish Project.toml and README

* Get docs to cover core + extensions also

* Fix typo

* push things properly

* amend paths too

* fix again

.gitignore

@@ -1,4 +1,5 @@
 /Manifest.toml
+/GeometryOpsCore/Manifest.toml
 /docs/build/
 /docs/src/source/
 .vscode/

GeometryOpsCore/Project.toml

@@ -0,0 +1,9 @@
+name = "GeometryOpsCore"
+uuid = "05efe853-fabf-41c8-927e-7063c8b9f013"
+authors = ["Anshul Singhvi <[email protected]> and contributors"]
+version = "0.1.0"
+
+[deps]
+DataAPI = "9a962f9c-6df0-11e9-0e5d-c546b8b5ee8a"
+GeoInterface = "cf35fbd7-0cd7-5166-be24-54bfbe79505f"
+Tables = "bd369af6-aec1-5ad0-b16a-f7cc5008161c"

GeometryOpsCore/README.md

@@ -0,0 +1,8 @@
+# GeometryOpsCore
+
+This is a "core" package for [GeometryOps.jl](https://github.com/JuliaGeo/GeometryOps.jl), that defines some basic primitive functions and types for GeometryOps.
+
+Generally, you would depend on this to use either the GeometryOps types (like `Linear`, `Spherical`, etc) or the primitive functions like `apply`, `applyreduce`, `flatten`, etc. 
+All of these are also accessible from GeometryOps, so it's preferable that you use GeometryOps directly.
+
+Tests are in the main GeometryOps tests, we don't have separate tests for GeometryOpsCore since it's in a monorepo structure.

GeometryOpsCore/src/GeometryOpsCore.jl

@@ -0,0 +1,28 @@
+module GeometryOpsCore
+
+using Base.Threads: nthreads, @threads, @spawn
+
+import GeoInterface
+import GeoInterface as GI
+import GeoInterface: Extents
+
+# Import all names from GeoInterface and Extents, so users can do `GO.extent` or `GO.trait`.
+for name in names(GeoInterface)
+    @eval using GeoInterface: $name
+end
+for name in names(Extents)
+    @eval using GeoInterface.Extents: $name
+end
+
+using Tables
+using DataAPI
+
+include("keyword_docs.jl")
+include("types.jl")
+
+include("apply.jl")
+include("applyreduce.jl")
+include("other_primitives.jl")
+include("geometry_utils.jl")
+
+end