Proposal to address I18N-ISSUE-179: Scope of document language label

Proposal to address I18N-ISSUE-179: Scope of document language label
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Issue:  There is no a way to declare the language of a TURTLE document
("the scope of this document has language 'xx-yy'")

Rational: If the author is typing a lot of language tagged literals in
the same language it is annoying to have to repeat the language each
time.

Proposed solution from I18N WG: There should be a way to declare the
language of a TURTLE document ("the scope of this document has
language 'xx-yy'")

Objections:

* Turtle is a well deployed language not a new design. The same issue
exists in SPARQL 1.0 and SPARQL 1.1 which did not draw this objection.

* Changing bare literals "example" to be language tagged would likely
cause more confusion as they are already changing to xsd:string.

* Any method of defaulting bare literals "example" to a specific
language would make it harder to write down xsd:string's\

* As Turtle is a data format not a 'content' format it is far more
likely for Turtle to contain many languages then HTML documents do.

PROPOSAL: Turtle will not add a method to declare the language of the document.