Updated monad tutorial

[Jeff Newbern]

Hello,

I would like to thank everyone for their feedback on the monad tutorial
I posted earlier.  Based on that feedback, I have expanded and corrected
the tutorial at www.nomaware.com/monads/html/index.html

The primary changes are:
 - vastly expanded section on monad transformers
 - additional examples of monad transformers, including multiple
   transformers in a stack 
 - added examples for liftM, guard, ap and msum
 - consistent use of "action" in IO monad "computation" in all others
 - made language more precise when discussing the IO type constructor
 - fixed typos, cleaned up some code in examples
 
I am sufficiently pleased with this version to call it 1.0, but I still
welcome any and all feedback.

Thanks,
Jeff Newbern
-- 
Jeff Newbern <jnewbern@nomaware.com>
Nomaware, Inc.