Seperate set and assign presets. Also add queury messages to mqtt

[QuantumEntangledAndy]

Missing commit from #92

Adds:

• Readme updates
• Preset assign seperate from set
• Preset query in MQTT interface

[QuantumEntangledAndy]

New mqtt messages are:

• /control/ptz/preset [id] Move the camera to a PTZ preset
• /control/ptz/assign [id] [name] Set the current PTZ position to a preset ID and name
• /query/ptz/preset Request that the camera reports its PTZ presets
• /status/ptz/preset Sent in reply to a /query/ptz/preset an XML encoded version of the PTZ presets

New command line are as follows:

• Rotate left by 32

  neolink ptz --config=config.toml CameraName control 32 left

• Rotate left by 32 at speed 10 (speed not supported on most camera)

  neolink ptz --config=config.toml CameraName control 32 left 10

• Print the list of preset positions

  neolink ptz --config=config.toml CameraName preset

• Move the camera to preset ID 0

  neolink ptz --config=config.toml CameraName preset 0

• Save the current position as preset ID 0 with name PresetName

  neolink ptz --config=config.toml CameraName assign 0 PresetName