Upgrade to new API

[Planeshifter]

• support for typed array inputs
• do not mutate by default (-> new copy option)
• accessor and dtype options
• tests
• switch from coveralls to codecov.io
• updated dotfiles, Makefile etc.

Open question:
Shall we support matrix inputs? If so, how should they be treated? Return all unique columns / rows or all unique elements from the underlying data store as a simple array? Or not necessary at all?

Pull request resolves compute-io/todo#120 and compute-io/todo#35

[kgryte]

For matrices, return as a linear array according to a specified dtype.

[kgryte]

How do you feel about returning indices? See compute-find.

[kgryte]

And do we want to support preserving the order of occurrence? Right now, results are returned sorted. If we do want to preserve order, then will need to use an additional (alternative) algo.