Make :data() on an empty Tensor return nil rather than segfault.
Merge pull request #60 from timharley/master

Make :data() on an empty Tensor return nil rather than segfault.
making travis build-logs cleaner!
added eigen-value clarification
disable clang in travis till the problem is figured out in a separate branch
checks for self in FFI wrappers
Fix typo of n by m

line 140, it should be n-by-m rather than m-by-m
Merge pull request #66 from Grisson/patch-1

Fix typo of n by m