apply patch from Samo Pahor that allows from= and to= to be the same as well as updates to documentation regarding which contracts are currently active and which are delisted.  Thanks Samo

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/twsinstrument@428 edb9625f-4e0d-4859-8d74-9fd3b1da38cb