Control extruder

Example request

{
  "target": {
    "command": "target",
    "targets": {
      "tool0": 220
    }
  },
  "offset": {
    "command": "offset",
    "offsets": {
      "tool0": 10
    }
  },
  "select": {
    "command": "select",
    "tool": "tool0"
  },
  "extrude": {
    "command": "extrude",
    "amount": 5
  },
  "retract": {
    "command": "extrude",
    "amount": -3
  },
  "flowrate": {
    "command": "flowrate",
    "amount": 95
  }
}