Flood control does not take Replies into account

[Timo-Breumelhof]

Describe the bug

While fixing #79
I noticed that replies are not accounted for the check for the flood control.
The reason for this is that while saving a reply, the LastPostDate is not saved.
And that's used for the Flood test.

Software Versions

• DNN: 09.08.00
• Module: 06.05.01

To Reproduce

Steps to reproduce the behavior:
See #79, notice that Replies don't fire the Flood control.

Expected behavior

So there are a few questions:
A. Do we want Replies to taken into account for Flood control?
B. If yes, how do we support this?
IMO We should add a DB field LastReplyDate and add that to the Flood check. Thought?

@hismightiness @skamphuis

[WillStrohl]

Yes, I think we definitely should add that field and include replies in the flood control.