certlib updates to support add-include-book-dir! and structure things a bit more nicely: fixes bug 158

git-svn-id: http://acl2-books.googlecode.com/svn/trunk@2579 303c5b2c-9740-0410-b014-fd8f9db7be32
eliminate a sort of dependency loop between deflist and strings/defs-program

git-svn-id: http://acl2-books.googlecode.com/svn/trunk@2580 303c5b2c-9740-0410-b014-fd8f9db7be32
fix breakage from removing strings/defs-program from std/util/deflist

git-svn-id: http://acl2-books.googlecode.com/svn/trunk@2581 303c5b2c-9740-0410-b014-fd8f9db7be32