Extend Recording to multiple vehicles

[rajat2004]

New Additions -

1. Info of all vehicles is recorded (with additional column VehicleName), VehicleName parameter in Cameras field to specify specfic vehcile to use the camera from
2. Folder field in settings to change the directory to store data in

Example settings -

{
    "SettingsVersion": 1.2,
    "SimMode": "Car",

    "Vehicles": {
        "Car1": {
          "VehicleType": "PhysXCar",
          "AutoCreate": true
        },
        "Car2": {
          "VehicleType": "PhysXCar",
          "AutoCreate": true,
          "X": 0, "Y": 10, "Z": 0
        }
    },
    "Recording": {
        "RecordOnMove": false,
        "RecordInterval": 1,
        "Cameras": [
            { "CameraName": "0", "ImageType": 0, "PixelsAsFloat": false, "VehicleName": "Car1", "Compress": true },
            { "CameraName": "0", "ImageType": 5, "PixelsAsFloat": false, "VehicleName": "Car1", "Compress": true },
            { "CameraName": "0", "ImageType": 0, "PixelsAsFloat": false, "VehicleName": "Car2", "Compress": true }
        ]
    }

}

Recording - 2020-07-11-11-48-51.zip

Testing -

• Multiple Vehicles, with no recording settings (Scene image from each vehicle)
• Multiple Vehicles, specific sensor settings (Settings above)
• Single vehicle, no settings (Scene from that vehicle, former behaviour)

TODO:

• Update docs
• Unity implementation

Further possible additions -

• Allow user to specify directory to store recordings in (Replacement for Documents)
• Currently saving no images is not possible (For some reason this leads to an error in writing to file, even though the file has been created, and there are lines in it already)
  - I suspect this might be a race condition for the first write, since there are no images, no rendering and saving of images is required, so writing of pose data is happening almost instantaneously, but the file to write the data in hasn't still been created.(Haven't confirmed this though, just a thought)

Any testing (especially of Folder on Windows) or suggestions would be great!

Came to mind when working on #2841
Related older issue #1346, Also includes the fix proposed in #1414

[rajat2004]

Branch got messed up, closing in favour of #2861