haskell/Makefile: automatically run with number of threads equal to cpu cores
haskell/EqOptimizer.hs: disable parallelism in optimize when single-threaded
haskell/Makefile: target 'all' no longer forces recompilation
haskell/EqOptimizer.hs: first pass of constraints; remove redundant weights parameter in optimize
haskell/EqOptimizer.hs: add -Wall to GHC_FLAGS