Hide error panel on rebuild.
Hide error panel on rebuild.

Makes UI feel slicker as a successful rebuild takes long (>= 1 second).

Bodigrim/SublimeHaskell,hcarvalhoalves/SublimeHaskell,bscottm/SublimeHaskell,kgadek/SublimeHaskell,kgadek/SublimeHaskell,bscottm/SublimeHaskell,hcarvalhoalves/SublimeHaskell,SublimeHaskell/SublimeHaskell,SublimeHaskell/SublimeHaskell,Bodigrim/SublimeHaskell,tomv564/SublimeHaskell,tomv564/SublimeHaskell