fix(chatty): Performance tuning.

For truncated posts, show only 10 recent replies in flat mode. Scroll adjustments happen in $timeout instead of immediate (seems to fix blippy scrolls).
fix(chatty): Clean up tag usage to limit to supported tags only.
style(chatty): Change {{}} expression to ng-bind.
fix(chatty): Change binding to one time for performance.
fix(chatty): Adjust ng-ifs for performance.
chore(chatty): Update dependencies.
chore(chatty): Update dependencies.
fix(chatty): When cleaning html for oneline, replace with a space instead of empty string.
Style tweaks.