implement print speed control

[DutchmanNL]

issue as reference:

{
    "print": {
        "sequence_id": "0",
        "command": "print_speed",
        "param": "2" // Print speed level as a string
                     // 1 = silent
                     // 2 = standard
                     // 3 = sport
                     // 4 = ludicrous
    }
}