cgal tests failing

[alecjacobson]

@qnzhou maybe you could take a look?

[qnzhou]

Hmmm, the bug seems to be related in loading binary ply file instead of CGAL or mesh boolean, and the bug only show up in release mode on my machine. :(

./build/igl_tests
...
[----------] 3 tests from readPLY
[ RUN      ] readPLY.file_does_not_exist
[       OK ] readPLY.file_does_not_exist (0 ms)
[ RUN      ] readPLY.cube
[       OK ] readPLY.cube (1 ms)
[ RUN      ] readPLY.two_boxes_bad_self_union
PLY ERROR: fread() failed -- aborting.
make[2]: *** [include/igl/CMakeFiles/run_igl_tests] Error 1
make[1]: *** [include/igl/CMakeFiles/run_igl_tests.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....

It is likely a memory related bug because enabling/disabling other tests seems to have influence on the success of this test, but the failure point is always in Greg Turk's ply.h. The offending PLY file is data/two-boxes-bad-self-union.ply

Blender, Meshlab, MeshMixer are all able to open the file without error.