Generate Linux man pages when generating docs.
Remove temporary file generated by s_docs
Pick a better page for the developer man page.
Add a rules to configure and the top-level Makefile to generate the manual pages if they doesn't exist and doxygen is available.
Make sure man pages are installed in the right categories.

Seems that the autoconf code that does this automatically doesn't work
in our case:
http://lists.gnu.org/archive/html/automake/2004-03/msg00169.html
Merge pull request #942 from wiredtiger/man-pages

Generate Linux man pages when generating docs.