switch SAFE and CORE to sigilless params
Add deprecation notice to SAFE.setting.
[SAFE.setting] restricted &rmdir
mask &rename in SAFE.setting
forbid mkdir in SAFE.setting
forbid more functions in SAFE.setting
Add first cut of SAFE.setting, for the benefit of p6eval. Plenty miss…
…ing, but should make it clear to other interested folks how to do more.