made the pack completely portable and wrote relevent bat files to go with it

gitportable/usr/share/vim/vim91/indent/mail.vim

@@ -0,0 +1,15 @@
+" Vim indent file
+" Language:	Mail
+" Maintainer:	The Vim Project <https://github.com/vim/vim>
+" Last Change:	2023 Aug 13
+
+if exists("b:did_indent")
+  finish
+endif
+let b:did_indent = 1
+
+" What works best is auto-indenting, disable other indenting.
+" For formatting see the ftplugin.
+setlocal autoindent nosmartindent nocindent indentexpr=
+
+let b:undo_indent = "setl ai< cin< inde< si<"