wmllint: split introduction into labeled sections for clarity

Also, the top paragraphs, aimed at the core developers, have been moved to
the bottom, to get to the information key to general users.
wmlscope: import glob for Windows shell

The Windows cmd shell will not expand a globbed argument by default, in
fact it will make the argument invalid. Importing and utilizing the glob
module is needed for x-platform.

Globbing is especially important for breaking up the subtree, so wmlscope
doesn't give off "more than one resource/definition is visible here"
errors.
wmltools: cite define locations when "more than one definition" is visible

When "more than one resource" is visible, wmlscope tells you where they
are.  Now it will do the same for macro definitions.
wmltools: fix wmlscope crash in collection of unresolved macro calls

While testing wmlscope without including data/core, which guarantees lots
of "unresolved" references, I got a crash pointing to this line with the
traceback: "NameError: global name 'args' is not defined".

At first, I thought the crash might have been caused by my splitting out
parse_macroref into its own function, several months ago. However, the
line is at the wrong indentation level for those "args" to be the variable
referenced here. So what "args" might have been intended?

After tracking down the commit that added "args=args" to this line, I've
concluded that this was simply a mistake. ESR isn't around to ask anymore,
but if a macro was never defined, or is not called correctly, what "args"
could be relevant?