Preliminary isSortedList added in C.  Hooked into is.sorted at R level and quickly tested at console.  Now needs tests and for is.sorted to be passed a DT to potentially avoid fastorder. Currently is.sorted is only passed vectors (the result of fastorder).

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/datatable@1069 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
setnames(DT,"oldname","newname") no longer complains about duplicated column names in DT so long as oldname is unique and unambiguous.

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/datatable@1070 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Extra test for setnames

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/datatable@1071 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Merge branch 'refs/heads/r-forge-git-svn-local'