Merge in current Win32 version. Almost no Unix code touched.

Merge in current Win32 version. Almost no Unix code touched.

	* README.win32: More text.

	* config.h.win32 glibconfig.h.win32: Update to match the
	corresponding generated files on Unix.

	* makefile.msc: Update with new source files, and gthread
 	library. Use the compiler flag -MD instead of using -D_DLL and
	"/nodefaultlib:libc msvcrt.lib" in the link phase.

	* glib.def: Include new functions, drop removed ones.

	* glib.h: Add comments about main loop and polling on Win32. (In
	general, it's only for the GIMP's use.) Add Win32 IO Channel
	functions. Remove the obsoleted old IO Channel stuff (which was
	in #if 0 already).

	* giowin32.c: New file.

	* gmain.c: Include config.h, conditionalize <sys/time.h>
 	inclusion.  Add g_poll implementation for Win32 (only for the
 	GIMP's needs for now, it's hard or even impossible to be as clean
 	and generic as on Unix). Implement g_get_current_time on Win32. If
 	threads aren't supported, don't try to wake up main thread's
 	loop. On Win32, use a semaphore and not a pipe to wake up the main
 	loop.

	* gmessages.c: On Win32, allocate a console window if the standard
	output handle is invalid before writing to stdout, and reopen stdout
	to that console window.

	* giochannel.c: Conditionalize unistd.h inclusion. Some indentation
	cleanup.

	* gstrfuncs.c: Include <signal.h>.

	* gutils.c: On Win32, also check the HOMEDRIVE and HOMEPATH
	environment variables.

	* gmodule-dl.c gmodule-dld.c: In
 	_g_module_build_path, don't add the "lib" prefix and
 	".so" or ".sl" suffix if already there.

	* gmodule-win32.c: Likewise for the ".dll" suffix.

	* gthread-posix.c: Conditionalize <sys/time.h> inclusion.