Add syntax files from upstream vim repository

indent/mf.vim

@@ -0,0 +1,10 @@
+if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'vim') == -1
+  
+" METAFONT indent file
+" Language:    METAFONT
+" Maintainer:  Nicola Vitacolonna <nvitacolonna@gmail.com>
+" Last Change: 2016 Oct 1
+
+runtime! indent/mp.vim
+
+endif