Make "fewerBraces" available outside snapshot releases

More generally, I don’t quite understand the rationale behind disabling experimental feature flags but for nightly/snapshot versions. I have a DSL project, hence my users basically use the compiler itself, through the scripting engine/REPL. I expect them to use release versions. It basically bars me using experimental features, for instance generic number literals, which is unfortunate for a math DSL, as it is.