emit switches in relooper

Merge branch 'relooper-improvements' of github.com:int3/emscripten in…

…to incoming

reduce indentation in relooper

v 1.5.0

remove break labels more aggresively, with a refined natural flow ana…

…lysis

disabled support for hoisting back into loops in relooper

remove more unneeded break and continue statements in relooper