More robust check for validate_probablities().
Merge branch 'master' of github.com:dit/dit
Print out info about Cython.
Print out result of has_cython(), if Cython not found.
Try usin eval instead of exec.
Install NumPy on TravisCI.
Also, add message when NumPy not found during install.
Add back accidentally removed line to install Cython for TravisCI.