include a projection test for validation

the reprojection error seems to be quite large, we need 8px for the test
to pass by comparing the stored pixel coordinates with the computed
coordinates using ImageProjectiGeometry. As we are not testing the
projection, but loading the file, I guess this is fine. But still keep
this in mind...

test/runtests.jl

@@ -2,18 +2,25 @@ using FileIO
 using Test
 using BundlerIO
 using Downloads
+using ImageProjectiveGeometry
 
 @testset "BundlerIO" begin
     # download an example file
     url = "https://raw.githubusercontent.com/snavely/bundler_sfm/master/examples/kermit/results.example/bundle.out"
     filepath = tempdir()*"/bundle.out"
-		Downloads.download(url, filepath)
+    Downloads.download(url, filepath)
 
     bundle = load(filepath)
     @test length(bundle.cameras) == 11
     @test length(bundle.points) == 634
     @test length(bundle.views) == 2039
     @test bundle.views[(4,452)] == [-40.93, -5.87]
+    # test the projections. the errors are surprisingly large...
+    for (cam_id, point_id) in keys(bundle.views)
+	p = bundle.points[point_id]
+	cam = bundle.cameras[cam_id]
+	@test isapprox(cameraproject(cam, collect(p.coords)), bundle.views[(cam_id, point_id)], atol=8.) # figure out if we can reduce the tolerance
+    end
     save(filepath, bundle)
     rm(filepath)
 end