Sending a reply results in autoscrolling to top of conversation pane

[sssoleileraaa]

STR

1. Send enough replies so that you can see the scrollbar appear in the conversation pane and see how you are autoscrolled to the top of this window.

This code may need to be re-examined:

securedrop-client/securedrop_client/gui/widgets.py

Lines 2179 to 2181 in ff394d5

	# Completely unintuitive way to ensure the view remains scrolled to the bottom.
	sb = self.scroll.verticalScrollBar()
	sb.rangeChanged.connect(self.update_conversation_position)

[deeplow]

I definitely remember doing this part. The change was introduced in one of my PRs (#249). At the time it seemed to work, but the code was indeed a bit fragile and needs re-examining.