[boost] FC++: monads

Monads Monads are a work in progress. I think they have great potential, but they aren't yet "release quality" like the rest of the library. In any case, they are "at the bottom" of the dependency graph, so they can easily be included or removed. Point being, I would prefer it if people don't spend too much time debating them; it may be easier to just say "drop this component for now; if the library gets accepted, you may try again later"--that would be fine with me, especially if it expedites the review of other portions of the library. -- -Brian McNamara (lorgon@cc.gatech.edu)