Replaces samePhoneMarker/samePhoneResponsePrefix with:
- messagePrefix: prefix for all inbound messages
- Default: '[warelay]' if no allowFrom, else ''
- responsePrefix: prefix for all outbound replies
Also adds timestamp options:
- timestampPrefix: boolean to enable [Nov 29 06:30] format
- timestampTimezone: IANA timezone (default UTC)
Updated README with new config table entries.