message: fix: block messages if otr session is ended
diff: @@ -3,7 +3,6 @@ import PluginAPI from '../../plugin/PluginAPI'
  import { EncryptionPlugin } from '../../plugin/EncryptionPlugin'
  import Contact from '../../Contact'
  import Message from '../../Message'
  -import { DIRECTION } from '../../Message.interface'
  import Session from './Session'
  import DSA from 'otr/lib/dsa'
  import Options from '../../Options'
  @@ -100,11 +99,9 @@ export default class OTRPlugin extends EncryptionPlugin {
  return this.getSession(contact).then((session: Session) => {
  if (session.isEnded()) {
  - //@TODO block this message
  - message.setDirection(DIRECTION.SYS);
  - message.setPlaintextMessage('This message was not send');
  + contact.addSystemMessage(Translation.t('your_message_wasnt_send_please_end_your_private_conversation'));
  - return message;
  + throw new Error('OTR session is ended');
  } else if (session.isEncrypted()) {
  return session.processMessage(message, 'encryptMessage');
  } else {
  