- Add separate User and RealName config fields (fall back to Nick)
- Make RequestCaps configurable (defaults to server-time, message-tags)
- Refactor isBotMentioned into nickMentionedAt returning position;
stripBotMention now uses nickMentionedAt internally
- Replace custom isAlphanumeric with unicode.IsLetter/unicode.IsDigit
- Update tests for new nickMentionedAt function