[BRLTTY] jumpy bumps

[Brian Tew]

> I would like brltty to not move at all unless I Tell it to.
Is this possible?  I have played with cursor tracking, cursor visibility
and sliding window settings, but even with all these off it still jumps when new text comes.

Say I am chatting in irc.  If the chat is moving at all fast
I cannot read one comment before the display is jerked to the next.

I am using a braillesense u2 and desktop &86/64 with ubuntu.

Thanks.