v2.2.0

• Add frame.get_slice() method, which constructs a new Frame based on index bounds
• Add frame.copy() method, which additionally handles Waterfall() object copying
• Add frame.integrate() method, to easily construct spectra or time series data
• Add frame.from_backend_params(), to construct an empty frame based on data reduction parameters
• Add frame.plot() and frame.bl_plot() as aliases for render() and bl_render()
• Add stg.array() to cast either a Frame or a numpy array to a numpy array
• Change end_index to stop_index
• Bugfix int_factor and support data parameter in from_backend_params
• Add stg.dedrift() function