merged webwork (alpha 2.5.1)

Combines files from
* David Gage
* Geoff Goehle   -- Achievement modules
* Bill Wheeler     -- LTI modules
* Grant He         -- Homework2, Classlist2, PGProblemEditor2, localization throughout
* Mike Gage      -- glue, warning system, xmlrpc, external editor, problem tester. 
* John Hsu        -- xmlrpc
* Pan Luo (xcompass)       -- shibboleth
* Arnie Pizer     -- misc


It seems to compile.  It will take a little time to configure unless you are already using the 
prelocal.conf, global.conf.dist, postlocal.conf   configuration.

Look at the README in   webwork2/conf

You can post issues to github.com/mgage for the time being.  I'll ask that this repo be pulled into
github.com/openwebwork pretty soon.