SFS Toolbox 2.3.0

Several improvements to WFS and NFC-HOA driving functions and impulse response interpolation.
For documentation of the SFS Toolbox, see http://matlab.sfstoolbox.org/.

NEWS:

    - default 2D WFS focused source is now a line sink
    - improve point selection and interpolation of impulse responses
    - speed up Parks-McClellan resampling method
    - change default value of conf.usebandpass to false
    - rename conf.wfs.t0 to conf.t0
    - rename and improve easyffft() to spectrum_from_signal()
    - rename and improve easyifft() to signal_from_spectrum()
    - correct amplitude values of WFS and NFC-HOA in time domain
    - fix default 2.5D WFS driving function in time domain
    - add time_response_point_source()
    - update amplitude and position of dirac in dummy_irs()
    - fix missing secondary source selection in ssr_brs_wfs()
    - add amplitude terms to WFS FIR pre-filter
    - fix Gauss-Legendre quadrature weights
    - add delay_offset as return value to NFC-HOA and ir funtions
    - fix handling of delay_offset in WFS time domain driving functions