Add autoloadTimelines user setting to configure timeline loading behavior

app/soapbox/actions/settings.js

@@ -31,6 +31,7 @@ export const defaultSettings = ImmutableMap({
   showExplanationBox: true,
   explanationBox: true,
   otpEnabled: false,
+  autoloadTimelines: true,
 
   systemFont: false,
   dyslexicFont: false,

app/soapbox/components/timeline_queue_button_header.js

@@ -1,11 +1,22 @@
 import React from 'react';
 import PropTypes from 'prop-types';
+import { connect } from 'react-redux';
 import { injectIntl } from 'react-intl';
 import { throttle } from 'lodash';
 import classNames from 'classnames';
 import Icon from 'soapbox/components/icon';
+import { getSettings } from 'soapbox/actions/settings';
 
-export default @injectIntl
+const mapStateToProps = state => {
+  const settings = getSettings(state);
+
+  return {
+    autoload: settings.get('autoloadTimelines'),
+  };
+};
+
+export default @connect(mapStateToProps)
+@injectIntl
 class TimelineQueueButtonHeader extends React.PureComponent {
 
   static propTypes = {

app/soapbox/features/preferences/index.js

@@ -230,6 +230,10 @@ class Preferences extends ImmutablePureComponent {
               label={<FormattedMessage id='preferences.fields.reduce_motion_label' defaultMessage='Reduce motion in animations' />}
               path={['reduceMotion']}
             />
+            <SettingsCheckbox
+              label={<FormattedMessage id='preferences.fields.autoload_timelines_label' defaultMessage='Automatically load new posts when scrolled to the top of the page' />}
+              path={['autoloadTimelines']}
+            />
             <SettingsCheckbox
               label={<FormattedMessage id='preferences.fields.underline_links_label' defaultMessage='Always underline links in posts' />}
               path={['underlineLinks']}