Removes propagate/convey terminology.

Among the more notable changes introduced in GNU GPLv3 is its
replacement of "copy" and "distribute" terminology of GNU GPLv2 with
the exotic defined terms "propagate" and "convey", which make
reference to local copyright law. The use of these terms has been
described as having achieved a greater degree of
"internationalization" of the GNU GPL.

The drafters of GNU GPLv3 assumed there was something sufficiently
problematic about the use in GNU GPLv2 of terms matching those of the
US Copyright Act (copy, distribute, derivative work) that a systematic
approach was taken to avoid reference to such terms. The
propagate/convey scheme was one aspect of this.

This continues to be a worthwhile and interesting experiment. In the
past 5 years of experience of software licensed under GNU GPLv3 the
use of these defined terms has not resulted in any particular problem
or difficulty, nor has it hindered adoption of the license so far as I
can tell.

Nevertheless, for GPL.next I propose that the propagate/convey scheme
be abandoned, because, while harmless and interesting, at the end of
the day it adds a layer of unnecessary marginal interpretive
complexity that appears unjustified by any possible benefit it might
provide.

As a practical matter, it is not really possible to apply "propagate"
and "convey" in typical free software contexts in the way that may
have been envisioned. Since free software development and distribution
involves effectively unquantifiable aggregations of
cross-jurisdictional transfers of software copies, it would seem that
in a typical case it would be quite difficult to pin down which local
law to apply. Of course this "problem", if it is really a problem,
arises under free software licenses using more conventional
terminology too. So nothing is gained by what ultimately appears to be
a superficial attempt to internationalize the terminology (except in a
purely political sense).

Indeed, it is a curious thing that when reasoning about free software
licenses it is practically necessary to hypothesize a harmonized
international system of exclusive copyright rights with equivalent
boundaries. This is so whether one uses an otherwise undefined term
that happens to find some use in one or more English-language local
copyright regimes (e.g. "distribute") or whether one attempts to map
GNU GPLv3 "convey" to some determined local law definition.

A choice of law clause (mainly a contract law concept) is the
traditional way to minimize some of this sort of complexity in other
contexts. The FSF, interestingly, has at times stated the view that
choice of law clauses in free software licenses are GPL-incompatible,
and I consider this to be GNU GPL interpretive orthodoxy. I believe
the historical concern (perhaps justified in some cases) was that of
selection of a jurisdiction that had laws markedly unfriendly to free
software.

For most individuals operating within the universe of GNU GPL-licensed
software and contemplating the differences in terminology between v2
and v3, it will be natural to assume that "propagate" and "convey" are
synonymous to v2's "copy" and "distribute", respectively.

In GNU GPLv3 the "propagate" definition is used mainly to provide the
basis for the "convey" definition. The counterpart term to "convey" in
GNU GPLv2, "distribute", is used in most other widely-used free
software licenses today. I believe it may even be used in some free
software licenses written from a European law perspective (though have
not checked that). True, some of these free software licenses have
choice of law clauses, but most don't. None of this has caused any
difficulty. We are left, then, with the conclusion that the main
benefit of the propagate/convey scheme is a political one. This is not
a good enough reason to keep it.