z.lua was missing some lines for z.cmd.

The auto-init for z.cmd was missing a couple of lines.  The HomeDir
line, in particular, is important because it enables Lua to find the
z.lua script.

z.lua

@@ -2703,6 +2703,8 @@ function z_windows_init(opts)
 	else
 		print('@echo off')
 		print('setlocal EnableDelayedExpansion')
+		print('set "HomeDir=%~dp0"') -- So that Lua can find the z.lua file.
+		print('set "PathSave=%PATH%"')
 		print('set "LuaExe=' .. os.interpreter() .. '"')
 		print('set "LuaScript=' .. os.scriptname() .. '"')
 		print(script_init_cmd)