FIX: Allow verify_integrity to work on general t_column. Improve messages.
Merge pull request #153 from danielballan/fix-integrity-assert

FIX : Allow verify_integrity to work on general t_column. Improve messages.
Docstring: formating (minor)
Merge pull request #158 from sciunto/patch-2

Docstring: formating (minor)
FIX: Import bug was introduced in fit_powerlaw. Add test.
Merge pull request #160 from danielballan/test-fit-powerlaw

FIX : Import bug was introduced in fit_powerlaw. Add test.