Use classes from rudel-connections.el in infinote backend
* infinote/rudel-infinote.el (rudel-infinote-backend::rudel-connect):
  changed name of instantiated class
  `rudel-infinote-client-connection' ->
  `rudel-infinote-client->server-connection'
* infinote/rudel-infinote-state.el (rudel-infinote-state::connection):
  changed type `rudel-infinote-client-connection' ->
  `rudel-infinote-client->server-connection'
* infinote/rudel-infinote-client.el (require rudel-connections): new
  require; superclass of `rudel-infinote-client->server-connection'
  (rudel-infinote-client->server-connection): added superclass
  `rudel-client->server-connection'
  (rudel-infinote-client->server-connection::initialize-instance):
  (rudel-infinote-client->server-connection::rudel-get-group):
  (rudel-infinote-client->server-connection::rudel-remove-group):
  (rudel-infinote-client->server-connection::rudel-find-node):
  (rudel-infinote-client->server-connection::rudel-add-node):
  (rudel-infinote-client->server-connection::rudel-send):
  (rudel-infinote-client->server-connection::rudel-disconnect):
  (rudel-infinote-client->server-connection::rudel-subscribe-to):
  (rudel-infinote-client->server-connection::rudel-unsubscribe-from):
  (rudel-infinote-client->server-connection::rudel-subscribe-session):
  (rudel-infinote-client->server-connection::rudel-local-insert):
  (rudel-infinote-client->server-connection::rudel-local-delete):
  (rudel-infinote-client->server-connection::rudel-local-operation):
  (rudel-infinote-client->server-connection::rudel-remote-operation):
  renamed class `rudel-infinote-client-connection' ->
  `rudel-infinote-client->server-connection'