fixing possible NPEs with uninitialized Option values not having a value, but empty being false.  We are inverting the 'empty' condition.  Before, class A { public Option<String> O }, new A().O.Select(s => s.ToString(); would NPE. This should fix that
Merge pull request #7 from vmarquez/OptionFix

fixing possible NPEs with uninitialized Option values not having a value...
Merge branch 'master' of https://github.com/NICTA/xsharpx
first try for a free monad dictionary implementation