improved NoteFormMixin, added Appel model and form in 'suivi'

suivi/notes.py

@@ -0,0 +1,13 @@
+from django.db import models
+from notes.models import Note
+
+class Appel(Note):
+
+    entrant = models.BooleanField( "Appel entrant ?")
+
+    def save(self, **kwargs):
+        print('save', self)
+        return super().save(**kwargs)
+
+    def note_labels(self):      return ["Reçu" if self.entrant else "Émis", self.created_by]
+    def note_bg_colors(self):   return ("warning", "info")