Make pre-selection of usernames optional when replying to a toot

Fixes #751

app/javascript/flavours/glitch/features/composer/index.js

@@ -102,6 +102,7 @@ function mapStateToProps (state) {
     anyMedia: state.getIn(['compose', 'media_attachments']).size > 0,
     spoilersAlwaysOn: spoilersAlwaysOn,
     mediaDescriptionConfirmation: state.getIn(['local_settings', 'confirm_missing_media_description']),
+    preselectOnReply: state.getIn(['local_settings', 'preselect_on_reply']),
   };
 };
 
@@ -328,13 +329,14 @@ class Composer extends React.Component {
       isSubmitting,
       preselectDate,
       text,
+      preselectOnReply,
     } = this.props;
     let selectionEnd, selectionStart;
 
     //  Caret/selection handling.
     if (focusDate !== prevProps.focusDate) {
       switch (true) {
-      case preselectDate !== prevProps.preselectDate:
+      case preselectDate !== prevProps.preselectDate && preselectOnReply:
         selectionStart = text.search(/\s/) + 1;
         selectionEnd = text.length;
         break;
@@ -533,6 +535,7 @@ Composer.propTypes = {
   anyMedia: PropTypes.bool,
   spoilersAlwaysOn: PropTypes.bool,
   mediaDescriptionConfirmation: PropTypes.bool,
+  preselectOnReply: PropTypes.bool,
 
   //  Dispatch props.
   onCancelReply: PropTypes.func,

app/javascript/flavours/glitch/features/local_settings/page/index.js

@@ -106,6 +106,14 @@ export default class LocalSettingsPage extends React.PureComponent {
         >
           <FormattedMessage id='settings.always_show_spoilers_field' defaultMessage='Always enable the Content Warning field' />
         </LocalSettingsPageItem>
+        <LocalSettingsPageItem
+          settings={settings}
+          item={['preselect_on_reply']}
+          id='mastodon-settings--preselect_on_reply'
+          onChange={onChange}
+        >
+          <FormattedMessage id='settings.preselect_on_reply' defaultMessage='Pre-select usernames past the first when replying to a toot with multiple participants' />
+        </LocalSettingsPageItem>
         <LocalSettingsPageItem
           settings={settings}
           item={['confirm_missing_media_description']}

app/javascript/flavours/glitch/reducers/local_settings.js

@@ -14,6 +14,7 @@ const initialState = ImmutableMap({
   show_reply_count : false,
   always_show_spoilers_field: false,
   confirm_missing_media_description: false,
+  preselect_on_reply: true,
   content_warnings : ImmutableMap({
     auto_unfold : false,
     filter      : null,