Merge pull request #2 from wxHaskell/master

Get up-to-date with wxHaskell:master
wxc/setup.hs now stops searching for wxWidgets when a compatible version is found

This solves bug report https://sourceforge.net/p/wxhaskell/bugs/96/
Merge https://github.com/HJvT/wxHaskell
Merge branch 'master' of https://github.com/wxHaskell/wxHaskell
Merge branch 'patch-2' of https://github.com/Vreugdsoft/wxHaskell
Merge branch 'master' of https://github.com/wxHaskell/wxHaskell
wxc/setup.hs now stops searching for wxWidgets when a compatible version is found

This solves bug report https://sourceforge.net/p/wxhaskell/bugs/96/
(the previous solution was not correct, because filterM is too strict.)