Bind MS_VERSION to $mapscript::VERSION in perl

[woodbri@…]

VERSION in a perl module is a "well know CONSTANT" that a lot of perl machinery
uses, for instance MakeMaker. The MS_VERSION value also be bound to
$mapscript::VERSION so that automatic version dependancy checking can be made
when building, installing, and use'ing Perl modules the include Perl/mapscript.

[sgillies@…]

I just read through the ExtUtils::MakeMaker docs and I dont't see that this will
help.  If you look at the variable stubs at the end of mapscript.pm you will see
that SWIG emits variables in an opaque way.

One fail-safe solution is to set a VERSION argument to WriteMakefile in 
the mapscript Makefile.PL.  This would require some attention at every
release ... but IMO the Perl makefile could use a bit more maintenance.
Hasn't been modified in almost 1.5 year.

Another idea I have is to spit the version into the mapscriptvars file.  Then
Makefile.PL could extract it and pass it in to WriteMakefile.  I'll probably
go this route.

[sgillies@…]

Fixed.  The UNIX/Linux and Win32 makefiles each output the mapserver version
to mapscriptvars file.  The version will be extracted by the Perl Makefile.PL
and Python setup.py scripts.