Clean up error/warning show code
Don't start new build if a build for the same project (name) is already running.

This is for both autobuild and build commands.

It avoids high CPU spikes for notoric savers (like me).
Small cleanup
Add Prelude functions to completions
Merge branch 'master' of https://github.com/SublimeHaskell/SublimeHaskell into completion-hints