V0.0    1994 Oct 09  First version, combining SloSweep and Sinewave
V0.0-01 1994 Oct 10  Use TDlgWindow as main window
                     Move sweep_running to main data segment
V0.0-02 1994 Oct 12  Get double-buffering working properly
                     Put sweep_running back in object data!
V1.0.0  1995 May 07  Version for Delphi 1.0
V1.1.0  1995 Oct 08  Better quality, 16-bit audio
V2.0.0  1996 Jun 01  Version for 32-bit Delphi
                     Add more output levels
                     Allow for smooth or stepped fast sweep
                     Improve generation to about 15-bit accuracy
                     Release to public domain
V2.0.2  1996 Dec 30  Add white noise option
V2.0.4  1997 Jan 10  Add manual slow sweep controlled by PageUp & PageDown keys
                     (Start button must have the focus)
                     Add two more output levels
                     Add octave markers
V2.0.6  1997 Mar 09  Add TrackBar for manual frequency control
                     Reversed interpretation of PageUp & PageDown keys
V2.1.0  1997 May 03  Replace output level buttons by slider control
                     Use 2-channel output buffer for all modes
                     Allow independent Left and Right frequencies
                     Allow in-phase, out-of-phase or independent channel levels
                     Add running LED
                     Add HTML documentation
V2.2.0  1997 Jun 01  Version for Delphi 3.0
                     Make sine table generator use symmetry for faster startup
                     Change max_buffer_samples to allow 1.3 seconds of audio
                       - this allows exactly 50ms per fast sweep segment
                     Correct two truncated buffer writes at end of slow sweep
                     Use array of pre-computed frequencies for slow sweep
                     Add ability to save sweeps as a file
                     Add experimental programmed sweep mode
V2.2.2  1997 Oct 06  Version for Delphi 3.01
                     Don't progress programmed mode
                     Add Pink noise mode
V2.2.4  1997 Nov 15  Add user-programmed sweep, frequencies saved in registry
                     Add variable slow sweep time
                     Add auto-save of state in registry
                     Build requiring VCL30.DPL run-time library
V2.2.6  1998 Feb 16  Optional de-click of fast sweep
V2.3.0  1998 Nov 17  Version for Delphi 4.0
                     Remove pink noise mode
                     Clean out old programming form code to compact the .EXE
V3.0.0  2000 Feb 07  Require registration for tech support or saving waveform
V3.1.0  2001 Jul 16  Version for Delphi 5
                     Support more wave output devices
V3.2.0  2002 Sep 25  Add pink noise
V3.3.0  2006 Mar 16  Add 90 degree phase
V3.4.0  2008 Feb 22  Remove requirement for the runtime library bundle
V3.5.0  2008 Feb 23  Version compiled with Delphi 2007
V3.5.2  2009 May 28  Add square-wave option
                     Add looped slow sweep (registered version)
                     Improve layout for large fonts
                     Add LED to start/stop button

Release V3.5.4.29
V3.5.4  2011 Mar 04  Add possibility to phase step every few seconds ..
                     .. make sure both channels are phase shifted
                     .. right-click on checkbox to adjust parameters
                     Always save settings on program exit
                     Always save settings on program exit

Release V3.5.6.30
V3.5.6  2012-Oct-18  Fix registration error

Release V3.6.2.32
V3.6.2  2013-Apr-06  Add impulse output ..
                     .. 175 Hz and 2205 Hz raised cosine
                     .. could be used to check speaker phasing
Release V3.7.2.35
V3.7.2  2014-Aug-21  Add trigger burst before audio sweep ..
                     .. fast sweep only
                     .. 2.0 KHz burst on the right-hand channel

Release V3.7.4.36
V3.7.4  2014-Sep-06  Correct hint for trigger burst

Release V3.7.6.38
V3.7.6  2015-Aug-10  Greater output attenuation range
                     Change default level to -20 dB


