[FIX+IMP] rma: usability

* IMP - Now the description will be an html son we can show rich styles
in the customers report.
* FIX - On locked sale orders it was need to unlock them to be able to open an RMA.
* IMP - Make the description label visible in the backend form so the
user can easily spot it.
* IMP - Added date and deadline filters.
* IMP - Added pending RMAs filter.
* IMP - Added late RMAs filter.
* IMP - Added danger decoration in tree view

rma/models/rma.py

@@ -176,7 +176,7 @@ class Rma(models.Model):
         copy=False,
         track_visibility="onchange",
     )
-    description = fields.Text(
+    description = fields.Html(
         states={
             'locked': [('readonly', True)],
             'cancelled': [('readonly', True)],