option to get "flat" result from Turtle serialiser

[indeyets]

N-Triples format is great for machine-parsing (one line per-triple), but it has issues with non-ASCII characters.

Turtle format is a superset of N-Triples and it doesn't have issues with non-ASCII characters, but default output of EasyRdf_Serialiser_Turtle is not compatible with line-parsing.

An option should be introduced, which would allow dumping "one line per-triple" variant using Turtle serialser