Documentation improvements + fixes (#55)

* Copy README to be the landing page for the docs

* Update make.jl

* Add an API page

* Add a bit more documentation in some places

* Revamped README

* Try to fix Makie issues with barycentric example

* Add a basic WIP API page

* Minor typo fixes

* Finally fix barycentric plot issues

* more barycentric fixes

* More pictures, remove readme from docs

* minor updates

README.md

@@ -9,21 +9,31 @@
 
 GeometryOps.jl is a package for geometric calculations on (primarily 2D) geometries.
 
-The driving idea behind this package is to unify all the disparate packages for geometric calculations in Julia, and make them GeoInterface.jl-compatible. We seem to be focusing primarily on 2/2.5D geometries for now.
+The driving idea behind this package is to unify all the disparate packages for geometric calculations in Julia, and make them [GeoInterface.jl](https://github.com/JuliaGeo/GeoInterface.jl)-compatible. We seem to be focusing primarily on 2/2.5D geometries for now.
 
 Most of the usecases are driven by GIS and similar Earth data workflows, so this might be a bit specialized towards that, but methods should always be general to any coordinate space.
 
+We welcome contributions, either as pull requests or discussion on issues!
+
 ## Methods 
 
-- Signed area, centroid, distance, etc
+GeometryOps tries to offer most of the basic geometry operations you'd need, implemented in pure Julia and accepting any GeoInterface.jl compatible type.
+
+- General geometry methods (OGC methods): `equals`, `extent`, `distance`, `crosses`, `contains`, `intersects`, etc
 - Targeted function application over large nested geometries (`apply`)
-- Line and polygon simplification
-- Generalized barycentric coordinates in polygons
-- OGC methods (crosses, contains, intersects, etc)
-- Proection of geometries between coordinate reference systems
+- `signed_area`, `centroid`, `distance`, etc for valid geometries
+- Line and polygon simplification (`simplify`)
+- Polygon clipping, `intersection`, `difference` and `union`
+- Generalized barycentric coordinates in polygons (`barycentric_coordinates`)
+- Projection of geometries between coordinate reference systems using [Proj.jl](https://github.com/JuliaGeo/Proj.jl)
+- Polygonization of raster images by contour detection (`polygonize`)
+
+See the "API" page in the docs for a more complete list!
 
 ### Planned additions
 
-- Polygon union, intersection and clipping
 - Arclength interpolation (absolute and relative)
-- Buffering, hulls
+- Buffering, hulls 
+- Some kind of `applyreduce` primitive ([#38](https://github.com/asinghvi17/GeometryOps.jl/issues/38))
+- Checks for valid geometries (empty linestrings, null points, etc) ([#14](https://github.com/asinghvi17/GeometryOps.jl/issues/14))
+- Operations on spherical (non-Euclidean) geometry ([#17](https://github.com/asinghvi17/GeometryOps.jl/issues/17))