Adapt conversations color for #Forez

lib/forez/main_forez_dev.dart

@@ -35,6 +35,7 @@ void main() {
     appName: "#Forez",
     appQuickDescription: tr("Events organisation in Forez plain"),
     unreadConversationColor: Colors.green.shade900,
+    defaultConversationColor: Colors.green.shade900,
     toursEntriesBuilder: buildTour,
     additionalLoading: () => ForezGroupHelper.refreshInfo(),
     mainRouteBuilder: (c, k) => ForezRoute(key: k),

lib/models/config.dart

@@ -24,6 +24,7 @@ class Config {
   final String appName;
   final String appQuickDescription;
   final Color unreadConversationColor;
+  final Color defaultConversationColor;
 
   // Entries for the welcome tour
   final TourEntriesBuilder toursEntriesBuilder;
@@ -44,6 +45,7 @@ class Config {
     this.primaryColorDark,
     this.appName = "Comunic",
     this.appQuickDescription,
+    this.defaultConversationColor,
     this.unreadConversationColor,
     this.toursEntriesBuilder,
     this.additionalLoading,

lib/ui/screens/conversation_screen.dart

@@ -7,6 +7,7 @@ import 'package:comunic/helpers/users_helper.dart';
 import 'package:comunic/lists/conversation_messages_list.dart';
 import 'package:comunic/lists/users_list.dart';
 import 'package:comunic/models/api_request.dart';
+import 'package:comunic/models/config.dart';
 import 'package:comunic/models/conversation.dart';
 import 'package:comunic/models/conversation_message.dart';
 import 'package:comunic/models/new_conversation_message.dart';
@@ -92,6 +93,7 @@ class _ConversationScreenState extends SafeState<ConversationScreen> {
   // Colors definition
   Color get _senderColor =>
       _conversation.color ??
+      config().defaultConversationColor ??
       /*(darkTheme() ? Color(0xff2b343b) :*/ Colors.blue.shade700; //);
 
   Color get _receiverColor =>
@@ -100,11 +102,13 @@ class _ConversationScreenState extends SafeState<ConversationScreen> {
   Color get _greyColor => Color(0xff8f8f8f);
 
   Color get _gradientColorStart =>
-      _conversation.color ??
+      (_conversation.color ?? config().defaultConversationColor)
+          ?.withOpacity(0.7) ??
       (darkTheme() ? Color(0xff00b6f3) : Colors.blue.shade300);
 
   Color get _gradientColorEnd =>
-      _conversation.color?.withOpacity(0.7) ??
+      _conversation.color ??
+      config().defaultConversationColor ??
       (darkTheme() ? Color(0xff0184dc) : Colors.blueAccent.shade700);
 
   Color get _separatorColor =>