added knownhosts color

vim/.vim/filetype.vim

@@ -0,0 +1 @@
+au BufNewFile,BufRead known_hosts setfiletype knownhosts

vim/.vim/syntax/knownhosts.vim

@@ -0,0 +1,9 @@
+setlocal iskeyword=@,48-57,_,192-255,#,-
+syntax match knownhostspubkey "AAAA[a-zA-Z0-9+/]\+[=]\{0,2}"
+highlight def link knownhostspubkey Special
+
+syn keyword sshalg ssh-rsa
+hi def link sshalg Identifier
+
+syn match knownhostsip "\<\(\d\{1,3}\.\)\{3}\d\{1,3}\>"
+hi def link knownhostsip Constant