Don't clean messages on offline

Dependencies

• [2] 55VVNPHU Log presence errors as errors
• [3] GSSXO6ZH Remove undelivireable messages
• [4] TGO4TIWU Fix README

Change contents

• replacement in src/xmpp/xmpp_connection.rs at line 681
  [2.35]→[2.35:136](∅→∅)
  − xmpp_parsers::presence::Type::Error | xmpp_parsers::presence::Type::Unavailable => {
  [2.35]

  [2.136]
  + xmpp_parsers::presence::Type::Error => {