push continuation into case branches in simplifier, re-enable some optimizations that depend on the environment
push continuation into case branches in simplifier, re-enable some optimizations that depend on the environment

darcs-hash:20061129104337-1a7c6-f7c383366b106bea7e6d7ffb3c443c5eebae6fdf

jimcrayne/jhc,jimcrayne/jhc,jimcrayne/jhc,jimcrayne/jhc