Rewrite ChangeLog as a Changes file in a simpler format

Changes is the more normal Perl convention for this file, and no
one seems to use GNU ChangeLog files any more.  Switch to free-form
descriptions of the changes instead.
Convert the build system to Module::Build

Move the scripts into a bin directory to match the standard
Module::Build layout.  Move perlpodstyle to pod and rename to
remove *.pod so that Module::Build (with some help) can do the
POD conversion correctly.

Increase the required Perl version to 5.006.  Everything else is
too old to test at this point.

Merge t/.cvsignore into the parent .gitignore.
Provide a hand-written Makefile.PL

The one automatically generated by Module::Build::Compat does not
correctly handle generation of man pages for scripts or for
perlpodstyle.  Resort to a hand-wrtten Makefile.PL for builds
inside Perl core.
Update README for the Module::Build build system

Change the instructions to prefer Module::Build, and update them
for no longer overwriting the Perl core modules on install.  Mention
the Makefile.PL for use in Perl core.  Increase the Perl version
requirement to 5.6.0 or later.

Remove an obsolete requirement for PerlIO, since podlators now uses
Encode to handle output encoding.
Add a Changes entry for no longer overwriting core modules
Bump the package and module versions to 4.00

Increase the version number of the package to be larger than any of
the previous version numbers of any of the modules, and change all
modules to use the same version as the overall podlators package.
Switch to a simple decimal version number to avoid complexity with
v-strings and portability to old versions of Perl.
Add style/module-version test and helper from rra-c-util

Add t/style/module-version.t as a test to ensure that all modules
in the distribution keep the same version number as the one
declared in Build.PL.  Add the supporting machinery from rra-c-util
for the test configuration it uses.  (This will be used later for
other standard tests.)
Add missing stopword in Pod::Man POD documentation
Ensure Pod::ParseLink SYNOPSIS passes use strict