systematic benchmarks for wordspace package (vs. plain R implementation)

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/wordspace@70 4e9de6a8-e6b3-4a20-ba07-35caea2ed9df
(minor bug fixes)

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/wordspace@71 4e9de6a8-e6b3-4a20-ba07-35caea2ed9df