Context menu on messages to deleted accounts

- messages from deleted chans still stay in global inbox
- this crated problems with account detection
- created NoAccount class for such accounts

src/bitmessageqt/account.py

@@ -54,7 +54,8 @@ def accountClass(address):
         else:
             subscription = SubscriptionAccount(address)
             if subscription.type != AccountMixin.SUBSCRIPTION:
-                return None
+                # e.g. deleted chan
+                return NoAccount(address)
         return subscription
     try:
         gateway = BMConfigParser().get(address, "gateway")
@@ -137,6 +138,17 @@ class BMAccount(object):
         self.toLabel = self.getLabel(toAddress)
 
 
+class NoAccount(BMAccount):
+    def __init__(self, address = None):
+        self.address = address
+        self.type = AccountMixin.NORMAL
+
+    def getLabel(self, address = None):
+        if address is None:
+            address = self.address
+        return address
+
+        
 class SubscriptionAccount(BMAccount):
     pass