Revise Model.read javadoc in light of RIOT readers.

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1518110 13f79535-47bb-0310-9956-ffa450edef68
Comments noting that text/plain for N-triples may be so unreliable as to be useless in practice.

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1518114 13f79535-47bb-0310-9956-ffa450edef68
Syntax determination.

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1518124 13f79535-47bb-0310-9956-ffa450edef68
Merge remote-tracking branch: upstream/trunk