Summary:
1) Update rasterizer/point rasterizer to accommodate fisheyecamera. Specifically, transform_points is in placement of explicit transform compositions.
2) In rasterizer unittests, update corresponding tests for rasterizer and point_rasterizer. Address comments to test fisheye against perspective camera when distortions are turned off.
3) Address comments to add end2end test for fisheyecameras. In test_render_meshes, fisheyecameras are added to camera enuerations whenever possible.
4) Test renderings with fisheyecameras of different params on cow mesh.
5) Use compositions for linear cameras whenever possible.
Reviewed By: kjchalup
Differential Revision: D38932736
fbshipit-source-id: 5b7074fc001f2390f4cf43c7267a8b37fd987547
