patch 8.0.1191: MS-Windows: missing 32 and 64 bit files in installer

Problem:    MS-Windows: missing 32 and 64 bit files in installer.
Solution:   Include both 32 and 64 bit GvimExt and related dll files. Remove
            old Windows code from the installer. (Ken Takata, closes #2144)

nsis/README.txt

@@ -1,5 +1,5 @@
 This builds a one-click install for Vim for Win32 using the Nullsoft
-Installation System (NSIS), available at http://www.nullsoft.com/free/nsis/
+Installation System (NSIS), available at http://nsis.sourceforge.net/
 
 To build the installable .exe:
 
@@ -17,8 +17,14 @@ To build the installable .exe:
 	uninstal.exe,
 	xxd/xxd.exe,
 
+    Then execute tools/rename.bat to rename the executables. (mv command is
+    required.)
+
 3.  Go to the GvimExt directory and build gvimext.dll (or get it from a binary
-    archive).
+    archive).  Both 64- and 32-bit versions are needed and should be placed
+    as follows:
+	64-bit: src/GvimExt/gvimext64.dll
+	32-bit: src/GvimExt/gvimext.dll
 
 4.  Go to the VisVim directory and build VisVim.dll (or get it from a binary
     archive).
@@ -27,13 +33,35 @@ To build the installable .exe:
     get them from a binary archive).
 
 6.  Get a "diff.exe" program and put it in the "../.." directory (above the
-    "vim61" directory, it's the same for all Vim versions).
+    "vim80" directory, it's the same for all Vim versions).
     You can find one in previous Vim versions or in this archive:
 		http://www.mossbayeng.com/~ron/vim/diffutils.tar.gz
+    Also put winpty32.dll and winpty-agent.exe there.
 
 7.  Do "make uganda.nsis.txt" in runtime/doc.  This requires sed, you may have
     to do this on Unix.  Make sure the file is in DOS file format!
 
+8.  Get gettext and iconv DLLs from the following site:
+	https://github.com/mlocati/gettext-iconv-windows/releases
+    Both 64- and 32-bit versions are needed.
+    Download the files gettextX.X.X.X-iconvX.XX-shared-{32,64}.zip, extract
+    DLLs and place them as follows:
+
+	<GETTEXT directory>
+	    |
+	    + gettext32/
+	    |	libintl-8.dll
+	    |	libiconv-2.dll
+	    |	libgcc_s_sjlj-1.dll
+	    |
+	    ` gettext64/
+		libintl-8.dll
+		libiconv-2.dll
+
+    The default <GETTEXT directory> is "..", however, you can change it by
+    passing /DGETTEXT=... option to the makensis command.
+
+
 Install NSIS if you didn't do that already.
 Also install UPX, if you want a compressed file.