Add option to stop sending read receipts (delabs MSC2285: private read receipts)

src/components/structures/TimelinePanel.tsx

@@ -1550,8 +1550,8 @@ class TimelinePanel extends React.Component<IProps, IState> {
         const isNodeInView = (node) => {
             if (node) {
                 const boundingRect = node.getBoundingClientRect();
-                if ((allowPartial && boundingRect.top < wrapperRect.bottom) ||
-                    (!allowPartial && boundingRect.bottom < wrapperRect.bottom)) {
+                if ((allowPartial && boundingRect.top <= wrapperRect.bottom) ||
+                    (!allowPartial && boundingRect.bottom <= wrapperRect.bottom)) {
                     return true;
                 }
             }