Make "frozen" (self-contained) app and executable program 
distributions for Mac, Windows, and Linux.

NOTE: the version of Python you use to run the build scripts
here is crucial--it's the version bundled with the app/exe.

NOTE [3.3]: the local copy of UserGuide.html in Windows and 
Linux frozen executables has links to files not included in 
these packages.  Because of this, the GUI's Help now opens 
the online version, and the UserGuide has a note referring 
local readers to the online copy.  The local copy probably
should be dropped eventually.  And ditto for other apps.