Rewritten the extract documentation and unified this in a single file and help page. Modified the lme4 extract method to do naive p values by default and fixed a minor bug there. Added the various packages to the ENHANCES: field in the DESCRIPTION file.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/texreg@132 edb9625f-4e0d-4859-8d74-9fd3b1da38cb