Fixed warnings in Data/Vector/Fusion/Stream/Monadic.hs
Fixed warnings in Data/Vector/Fusion/Stream/Monadic.hs

- Removed unused qualified import of Data.List
- Made the EMPTY_STREAM macro not shadow variables
- Eliminated unused bindings
- Eliminated shadowing

dolio/vector,seckcoder/vector,thomie/vector,phaazon/vector,phadej/vector