Add dynamic selection of boolean result writers
JENA-813 : Use IteratorConcat for iteraing over all graphs.
JENA-813 : Add comments on usage.
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/jena
Improve performance of DatasetGraphCollection (JENA-813)

Switches it to use IteratorConcat instead of IteratorCons.  Also
deprecates and switches all usages of IteratorCons to IteratorConcat.
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/jena

Merge together mine and Andy's javadoc changes

Conflicts:
	jena-arq/src/main/java/com/hp/hpl/jena/sparql/core/DatasetGraphCollection.java
	jena-arq/src/main/java/org/apache/jena/atlas/iterator/Iter.java
	jena-arq/src/main/java/org/apache/jena/atlas/iterator/IteratorConcat.java
Merge branch 'master' into hadoop-rdf

Merge in JENA-813 fixes
Reorganize Hadoop RDF IO packages

Moves the various different supported formats into their own packages to
make it easier to navigate the code base and find specific format
implementations
Further code reorg and TriX IO support

Further reorgs the packages in the hadoop-rdf-io module to make the code
easier to find.

Also adds support for TriX as an input and output format with
appropriate test cases