[Python-Dev] Finally fix installer to add Python to %PATH% on Windows

[Stephen J. Turnbull]

Paul Moore writes:

 > "Before any existing Python directories, otherwise at the end" is the
 > closest to what I suspect most users want (certainly it matches my
 > preferences, and anything else would have me manually editing PATH
 > anyway, so is of no use to me in practice).

Unfortunately, what is "no use to person X in practice" is a function
of X.  I suspect that's why this hasn't been done.

Specifically, it seems to me that there are use cases for each of

1.  Append (eg, if both python3 and python2 provide "python.exe", for
    experimental use of python3).
2.  Prepend (actually, not a use case; just common, and therefore
    "intuitive", practice).
3.  "Moore's rule" (put latest and greatest ahead of other versions
    but not interfere with previously installed apps).

Maybe it should be user-configurable.