Distarray's random functions should use their own random state.

Currently, `distarray.dist.random` uses `numpy.random` internally for its functions. This morphs NumPy's global random state, which might be unexpected to users who are using NumPy alongside distarray, and want to specify NumPy's random state.

Start in the distarray.dist.random module and trace where its functions use numpy.random. Check the existing random behavior and determine how to verify that calling distarray random functions no longer changes NumPy's global random state. Done means distarray random functions continue to work while NumPy's separately configured state remains unaffected.

Scritto dal modello di indicizzazione a partire dal testo della issue.