Added support for viewing the acl2+books combined manual with the
ACL2-Doc Emacs browser.  Pending: Handle package names in subtopics.

Restored DWIM feature for :doc (i.e., at the terminal).


git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1148 5d84a466-a78b-0930-a311-59b22171a541