Gajim doesn't handle unknow "type" messages the way it should

[vetetix]

When receiving a message with an unknown type (meaning, not 'chatroom', 'chat' or 'normal'), it considers it as a type='chat'. It is a problem with messages sent by sendxmpp, which uses type='message' (stupid non-existing type, if I understood what was told me).

RFC says: "if an application receives a message with no 'type' attribute or the application does not understand the value of the 'type' attribute provided, it MUST consider the message to be of type "normal" (i.e., "normal" is the default)."

Gajim doesn't respect the RFC.

[asterix]

(In [9826]) handle unknown message type as 'normal'. fixes #3977