v0.11.0

Changes:

• Set default ESC delay to 100ms and add the --escdelay command line
  argument for configuring it
• Update backend handling
  • Expect backends to send own messages in group chats back to nuqql with the
    sender <self> and handle these messages accordingly
  • Disable collecting accounts from backends and rely on the backend setting
    --push-accounts
  • Start purpled like other backends
• Requires nuqql-slixmppd v0.7.0, nuqql-matrixd v0.5.0,
  nuqql-matrixd-nio v0.2.0, nuqql-mattermostd v0.2.0, or purpled v0.6.0