0.5.0 (#52)

Added:

• Added forcats (#51 )
• Added base.is_ordered(), base.nlevels(), base.ordered(), base.rank(), base.order(), base.sort(), base.tabulate(), base.append(), base.prop_table() and base.proportions()
• Added gss_cat dataset

Fixed:

• Fixed an issue when Collection dealing with numpy.int_

Enhanced:

• Added base0_ argument for datar.get()
• Passed __calling_env to registered functions/verbs when used internally (this makes sure the library to be robust in different environments)