Fixed minor :doc bugs in mutual-recursion (thanks Jared), programming,
and equality-variants-details (thanks David Ra.).

Incorporated fix to time$ in centaur/ branch (svn revision 1117) made
by Jared Davis and Sol Swords.  Measured about 25x speedup for SBCL
(so, the gain isn't just for CCL).


git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1119 5d84a466-a78b-0930-a311-59b22171a541