Emit cost notes (5.2)

Emit cost notes (5.2)

• Protected : is pcall. Prefer pcall(obj.Kick, obj) when calling one method in a hot path.
• Long .: chains should become backtick interpolation or table.concat.
• clpp emit --no-banner drops the compiled-by comment.
• [[native]] on a function emits @native.
• to_bool(x) keeps not not (x).
• #if DEBUG / #if RELEASE drop dead branches to blank lines (line map preserved).