TST: This test currently fails.

Fix to follow immediately :-)
BF: Take care of sign-reversal in rotation matrix calculation.
BF: Calculation of eigen-vectors was confused by sign reversal.

This should fix this. No other side effects, as far as I could tell.
RF: Reorder the function a bit to short-circuit. Use broadcasting.
Fixed typo.
Merge pull request #334 from arokem/fix_vec2vec

Fix vec2vec