More stable blank node serialization

The toNQ method on PlainFactory now checks whether the value of the blank node includes the common prefix _: and acts accordingly.

Easier setup

No more setup calling when the default suits you. Hopefully this will make it work OOTB in the browser.

• Build a browser bundle b9037df
• Update the readme 598bda8
• Use a valid IRI for the defaultGraph 4e9f025
• Initialize with a PlainFactory instance by default 72c2e4a

v1.7.2...v2.0.0-0