Add tests for TransformExtendCombine

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1516514 13f79535-47bb-0310-9956-ffa450edef68
Add the Leviathan pow(?x, ?power) function (JENA-507)

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1516515 13f79535-47bb-0310-9956-ffa450edef68
Updated tests for Leviathan functions (JENA-507)

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1516516 13f79535-47bb-0310-9956-ffa450edef68
Add TransformExtendCombine which is used to flatten extend and assign operations together where possible.

Note that normal algebra construction does this automatically but in some cases it is useful to have this as a separate transform that may be applied

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1516517 13f79535-47bb-0310-9956-ffa450edef68
Merge remote-tracking branch: upstream/trunk