PHP ONVIF: Control network video devices with ONVIF protocol

This class can control network video devices with ONVIF protocol.

It can send HTTP SOAP requests to a network video device that supports the ONVIF protocol to perform several types of operations. Currently it can:

- Get the system date
- Get the system capabilities
- Get the video sources
- Get the existing profiles
- Get the available services
- Get information of the device information
- Get the URI of a stream
- Get the available presets
- Get information of a given node
- Go to a given preset
- Remove a given preset
- Set a given preset
- Perform a relative move
- Perform a relative move and zoom
- Perform an absolute move
- Start a continuous move
- Start a continuous move and zoom
- Stop a move