Create variable to ignore specific filetypes for highlight

doc/trailing-whitespace.txt

@@ -14,3 +14,13 @@ The repo is at http://github.com/bronson/vim-trailing-whitespace
 
 Originally based on http://vim.wikia.com/wiki/Highlight_unwanted_spaces
 
+------------------------------------------------------------------------------
+VARIABLES                                   *FixWhitespace-variables*
+
+                                       g:extra_whitespace_ignored_filetypes
+g:extra_whitespace_ignored_filetypes
+    You can set filetypes to be ignored for highlight into this variable.
+
+  let g:extra_whitespace_ignored_filetypes = ['unite', 'mkd']
+
+		The default value is [].

plugin/trailing-whitespace.vim

@@ -1,14 +1,25 @@
 if exists('loaded_trailing_whitespace_plugin') | finish | endif
 let loaded_trailing_whitespace_plugin = 1
 
+if !exists('g:extra_whitespace_ignored_filetypes')
+    let g:extra_whitespace_ignored_filetypes = []
+endif
+
+function! ShouldMatchWhitespace()
+    for ft in g:extra_whitespace_ignored_filetypes
+        if ft ==# &filetype | return 0 | endif
+    endfor
+    return 1
+endfunction
+
 " Highlight EOL whitespace, http://vim.wikia.com/wiki/Highlight_unwanted_spaces
 highlight ExtraWhitespace ctermbg=darkred guibg=#382424
 autocmd ColorScheme * highlight ExtraWhitespace ctermbg=red guibg=red
-autocmd BufWinEnter * match ExtraWhitespace /\s\+$/
+autocmd BufWinEnter * if ShouldMatchWhitespace() | match ExtraWhitespace /\s\+$/ | endif
 
 " The above flashes annoyingly while typing, be calmer in insert mode
-autocmd InsertLeave * match ExtraWhitespace /\s\+$/
-autocmd InsertEnter * match ExtraWhitespace /\s\+\%#\@<!$/
+autocmd InsertLeave * if ShouldMatchWhitespace() | match ExtraWhitespace /\s\+$/ | endif
+autocmd InsertEnter * if ShouldMatchWhitespace() | match ExtraWhitespace /\s\+\%#\@<!$/ | endif
 
 function! s:FixWhitespace(line1,line2)
     let l:save_cursor = getpos(".")