Bug#649530: [copyright-format] clearer definitions and more consistent License: stanza specification

[Jonathan Nieder <jrnieder@gmail.com>]

Ximin Luo wrote:

> the current DEP5 supports this and has it as an explicit example.

Relevant wording:

Section "Paragraphs", subsection "Stand-alone License Paragraph" says:

	Where a set of files are dual (tri, etc) licensed, or when the
	same license occurs multiple times, you can use a single-line
	License field and stand-alone License paragraphs to expand the
	license short names.

Problems:

 - the wording only permits stand-alone License paragraphs describing
   license short names, not short names with exceptions appended

 - the wording only permits stand-alone License paragraphs when a set
   of files has a complex license or the same license occurs multiple
   times, contradicting common practice of using stand-alone License
   paragraphs when convenient in simpler situations, too.

Section "Fields", subsection "License" says:

	Remaining lines: if left blank here, the file must include a
	stand-alone License paragraph matching each license short name
	listed on the first line.

Problem:

 - the wording only permits stand-alone License paragraphs describing
   license short names.

Section "License specification", subsection "Syntax" includes an
example of a License field for the license "GPL-2+ with OpenSSL
exception".  It does not make it clear whether this example is
suitable for Files paragraphs and stand-alone License paragraphs, or
only one of the two.

Hope that helps.
Jonathan