filenames on MS Windows: follow-up

[Allin C. <cot...@wf...>]

I'm attaching a patch against gnuplot git master which does what I 
mentioned in 
https://sourceforge.net/p/gnuplot/mailman/message/37141539/ That is, 
it allows wgnuplot.exe to accept via the Windows command-line 
unicode filenames that cannot be represented in the user's "system 
codepage", and to successfully to open such files.

This iteration of my patch uses native win32 APIs to perform the 
necessary recoding of filenames, as opposed to the previous 
iteration which used GLib.

I gave evidence in 
https://sourceforge.net/p/gnuplot/mailman/message/37143153/
that the patch is not disruptive of gnuplot's ability to open files 
named via the "load" command, in which case the encoding specified 
in the gnuplot script must be respected.

The patch is activated only when compiling the program for Windows, 
and then only when the symbol WIDE_ARGS is defined.

-- 
Allin Cottrell
Department of Economics
Wake Forest University