+ is.sorted moved from setkey down into fastorder.
+ fastorder returns NULL if sorted
+ fastorder now accepts vector as well as list of vector
+ Added vector isorted to fastorder.c and hooked up
+ isSortedList now accepts a subset of columns
+ bench()'s results now reflect sortedness nicely and make sense

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/datatable@1087 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
+ setDT returns the data.table again
+ added more checks to bench()

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/datatable@1088 edb9625f-4e0d-4859-8d74-9fd3b1da38cb