Kleisli and Do macros don't work with newest Sweet.js versions

[robotlolita]

Anyway, variable bindings in $do don't work with Sweet.js 0.5.x+ and Kleisli (...) > ... also breaks. The latter is probably easy to fix, $do might require some refactoring. I want to take a shoot at rewriting $do with Sweet.js 0.6.x custom patterns and stuff anyway, so this is mostly to remind myself of looking at it later.