rename release operator: R -> V, add weak until: W
rename release operator: R -> V, add weak until: W

same as SPIN syntax.

tulip-control/tulip-control,necozay/tulip-control,necozay/tulip-control,tulip-control/tulip-control,tulip-control/tulip-control,tulip-control/tulip-control,necozay/tulip-control,necozay/tulip-control,necozay/tulip-control