[maven-release-plugin] copy for tag 0.9.0

Users:

  • mix in multiple pools simultaneously
  • better mix priority management
  • fix "insufficient utxo amount for tx0"

Developers:

  • config:
    • set cli.mix.clients=null
    • add cli.mix.clientsPerPool=1
  • CLI_API 0.9
    • /rest/cli/config: removed 'clients'
    • /rest/pools: add tx0FeeTarget