Moved checking of zero columns only if the width is greater than 0.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/eventstudies@380 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Fixed event time conversion of firm returns based on other returns for each firm separately. Added function to compute adjusted returns.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/eventstudies@381 edb9625f-4e0d-4859-8d74-9fd3b1da38cb