Update README.md to use GeometryOps (#14)

Leads to a simpler API for the buffer ;)

README.md

@@ -15,6 +15,7 @@ The following example models the distribution of _Anopheles nili_, a malaria vec
 We'll use several other packages in addition to SpeciesDistributionModels
 ```julia
 using SpeciesDistributionModels, Rasters, RasterDataSources, GBIF2, LibGEOS, ArchGDAL, StatsBase
+import GeometryOps as GO
 import SpeciesDistributionModels as SDM
 ```
 
@@ -28,7 +29,7 @@ presence_points = unique(occurrences.geometry)
 
 The region of interest will be defined by a convex hull around our presence points, buffered by 5 degrees.
 ```julia
-roi = buffer(convexhull(MultiPoint(LibGEOS.to_geos.(presence_points))), 5)
+roi = GO.buffer(GO.convex_hull(presence_points), 5)
 ```
 
 Now we'll load bioclimatic variables from WorldClim, using `RasterDataSources` and `Rasters`.
@@ -133,4 +134,4 @@ parent:
   24.3333   0.00357797   0.00445221      0.00637058    0.00660174    0.00547219
   24.5      0.00610894   0.00443861      0.00616782    0.00583453    0.00602396
   24.6667   0.00440761   0.00360355      0.00649026    0.00615647    0.00665752
-```
+```