Allow keywords as enumeration member names

Enumeration member names cannot use reserved words such as String or Integer, so the Enumeration editor appends an underscore to them (giving String_), and users who want a prefix or suffix convention must apply it themselves. Enumeration values are always accessed as member names after a dot, either fully qualified (for example NativeType.Integer) or via the leading-dot shorthand (for example .clubs), and the parser already accepts reserved words after a dot; only the declaration position rejects them.

Requested: allow reserved words as enumeration member names, so an enumeration such as NativeType can declare String, Integer, and DateTime directly, and the Enumeration editor no longer needs to rename them.