Truncate long bot responses into two posts instead of mid-sentence cut-off

Summary

When snek the bot (botje.py) responds with an answer that exceeds the maximum message length, it should split the response into two separate posts. Currently, the response is cut off mid-sentence, which is not the desired behavior.

Steps to Reproduce

1. Trigger snek the bot to generate a response that is longer than the allowed message length.
2. Observe the bot's output.

Expected Behaviour

The bot should split the long response into two complete posts, preserving sentence boundaries.

Actual Behaviour

The response is cut off mid-sentence, resulting in an incomplete message.

Environment

Not provided.

Reported by retoor via DevPlace.