[chat] 10x more history, and don't force scroll unless it's at the bottom

[xX-Kuro-Xx]

Trade chat is really busy... and the chat UI makes it very very hard to read that's going on, because the text is always scrolling while I'm trying to read it.

1) please don't force scroll the text unless the scroller is at the BOTTOM... especially when i'm holding the scrollbar! (i.e. the scrollbar should anchor at the first line displayed on screen, not relative from the bottom of the chat history)

2) please add MUCH more text history. It could be a setting, or you could just make it huge. 10k lines?